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3D Printing Designs: Octopus Pencil Holder

Chapter 1. Octopus Pencil Holder

3D printing makes it easy to combine forms and functions. Why have just a pencil holder when you can have a pencil holder that looks like, say, a cute octopus? This project is an excellent starting project because it demonstrates a simple but versatile modeling technique that involves editing a simple mesh and smoothing it in order to go into more detail.

This project will involve simple selection techniques that are unique to the Edit Mode, modification commands in the edit mode, and applying modifiers to soften and combine shapes. This technique alone can be used to created unlimited cool things once mastered.

In this book, we will cover the following topics:

Planning the project
The first basic shape
Smoothing the mesh with modifiers
Bending the tentacles
Flattening the bottom
Renaming objects
Adding a pencil cup
Adding a face
Finishing touches

Bending the tentacles

Now, it's time to begin adding some details to the tentacles and give the model some personality.

Before moving ahead, let's take a look at another powerful tool when editing meshes, which is called loop cut or loop subdivide, which will be used while bending the tentacles. Loop cut adds points in the middle of an edge and all around a portion of the geometry. These points can then be transformed. Loop cut only works with edges or vertexes' select mode and will automatically switch modes when using them.

To perform a loop cut, execute the following steps:

Navigate to Mesh | Edges | Loop Subdivide from the 3D View menu, or press Ctrl + R.
Then, move the mouse pointer near an edge, and the loop cut suggestion will be suggested.
When the loop cut is where desired, click on the select mouse button or press Enter. At this point, the loop isn't set and can still be slid back and forth in order to decide an exact location.
When it is where desired, press Enter or the select mouse button again in order to finish the operation. At any time, the operation can be canceled by pressing the right mouse button or pressing the Esc key.
Now that we know how to perform a loop cut, let's go for why we are here, that is, bending the tentacles.
While still in the edit mode, switch to the vertex edit mode (Ctrl + Tab). Add a loop cut (Ctrl + R) to one of the tentacles. Place the cut at the default location in the middle of the tentacle:
After setting the loop cut, change the operator settings at the bottom of Tool Box and then change Number of Cuts to 2:
Deselect all points (A) and select the points at the end of the tentacle. Rotate (R) the points around the z axis (Z) and move (G) them along the x and y axes (Shift + Z) to bend the tentacle a bit:
Expand the selection (Ctrl + NumPad + the (+) sign). Again, rotate (R) the selection around the z axis (Z) and move (G) it along the x and y axes (Shift + Z) to bend the tentacle a bit more:
Expand the selection again. Rotate (R) and move (G) the tentacle, being careful to constrain the movement:
Check your tentacle. Adjust your view and make sure that from the front or side views, the twisty tentacle is still on the same level as the other tentacles and not twisted up and down. If it isn't, then your movements weren't constrained properly:
If not correct, then undo (Ctrl + Z) your movements and try again. There's a way to ensure that the movements are constrained properly. You can do this easily by doing all your transformation while in the top view (NumPad 7). It may be necessary to select points in the Wireframe view (Z) to get all the points and not just the ones on top.
Move to the next tentacle and cut it through loops. This time, while the loop location is being displayed, before clicking on the mouse or pressing Enter the first time, try to press the 2 key to quickly change the number of cuts to 2. This is a shortcut method that can be used optionally instead of changing the parameters after the cut:
Work around, cutting, selecting, moving, and rotating each tentacle. Give each one a different twist, being careful not to overlap them. If the tentacles overlap, the model won't print properly when exported:

Your octopus doesn't need to look exactly like this. Make it your own. When all the tentacles have been detailed, it should look much more like an octopus.

Tip

Some 3D printers won't be able to print this model if it's too big, so keep those tentacles tucked in and don't let them fly too far. The smaller 3D printer build areas are about 150 mm or 6 inches across. If the total width of your model is more than that, you'll need to think about the printer you're designing this for.

Flattening the bottom

A friendly 3D print needs to have a solid, flat base. There is more than one way the bottom of a model can be flattened. For one, the geometry can be edited to be flat. Alternatively, a floor object can be created and cut out of the object using a Boolean modifier. Since this project is using the subdivision surface modifier, editing the geometry can be complicated. So, the floor method will be used in this project.

Looking at the model from the front orthographic view (NumPad 1 and NumPad 5), it's clear that the parts of the tentacles that sit below the x and y axes (the red or green line depending on the view) is where the model needs to be cut off in order to create a flat, printable base:

So, let's get started:

First, exit the Edit Mode (Tab).
Ensure that the 3D cursor is at the 3D View origin point (Shift + C). Then, create a cube (Shift + A) by navigating to Mesh | Cube:
The cube cannot be seen in the solid view because it's completely inside the octopus, so with the cube still selected, switch to the local view (NumPad /) to view the cube by itself:
The cube is half above and half below the origin. Fortunately, there's an easy way to create a floor and ensure that no matter how it's scaled, the top remains on the XY plane.
In the Edit Mode (Tab), with all points selected (which should be selected by default; A is the hotkey if they're not), move (G) along the z axis (Z) by 1 unit (-1).
Then, exit the Edit Mode (Tab) and scale (S) the cube. Note that the top remains on the XY plane. This is because object transformations are made in relation to the object's origin. When the points were all moved in the Edit Mode, the origin wasn't affected. So now, when scaling the top, because it's in line with the cube's origin, it remains on the same plane:
Exit the local view (NumPad /) and scale (S) the cube until it covers the bottom of the octopus body:
In the Solid view (Z), it may look like the octopus has a flat bottom, but in the Wireframe View, (Z), it is clear that the cube is only hiding the bottom part. For the final model, the bottom needs to actually be flat:
Select the octopus body again, and in the Modifier tab, add a Boolean modifier:
Note
The Boolean modifier has the option of combining the selected object with another object in a number of ways; Intersect, Union, and Difference. Union joins the two object, so that they become one. Difference cuts the second object out of the first, and Intersect leaves only the part where the two objects overlapped. Boolean is a powerful tool and it's good to be aware of how to use it.

The following screenshot shows the three ways to combine selected objects with other objects:

Change the Operation value of the Boolean modifier to Difference. Click on the Object text field and choose Cube from the list that pops up:
Now the octopus body actually has a flat bottom that's suitable for 3D printing. This can be confirmed in the Wireframe view (Z):

The Boolean modifier is one of the most important tools in Blender that's used to create 3D printable objects. However, it can also be one of the most frustrating to use. The Boolean modifier demands that a mesh be clean and free from holes or problems. Even things that aren't obvious while looking at the mesh, such as duplicate points or flipped faces, can cause problems with the Boolean operation. If your Boolean operation isn't working, here are a few steps you can perform in order to try to fix it:

In the Edit Mode, select all the points (A), and in Tool Shelf (T), locate the Remove Doubles button in the Tools tab and click on it.
With all points still selected, switch to the Shading/UV tab, locate the Recalculate button, and click on it:
Now, exit the Edit Mode, and the Boolean modifier may work in many cases. If these fixes don't make the Boolean modifier work, then the best option may be to start over again, making sure that you perform all the steps correctly.

Adding a pencil cup

The octopus model looks appealing so far, but it can be functional as well. The plan for this project was a cup holder, so it needs to have the shape changed so that things can be put inside it:

To start, temporarily turn off the subdivision surface modifier by locating the Subsurf modifier in the Modifiers tab and clicking the eye icon in it. Now, the simplified geometry is easier to work with:
Go to the Face Select mode (Ctrl + Tab) in the Edit Mode (Tab). Now, select the topmost face of the octopus:
Switch to Wireframe (Z) and the Front Ortho view (NumPad 1) and extrude (E) the top face into the body. Stop just a little above the red x axis line:
Note
It may be necessary to scale (S) the bottom of the cup a little so that it fits inside the body.
After scaling the body will look this:
Now, the shape is generally right for a pencil holder. Turn the subdivision surface modifier back on by clicking on the eye icon in the Subsurf modifier in the Modifiers tab. You'll notice that the cup bottom is a bit too round to be a space-efficient cup:
In the Edit Mode, edges can be marked with Crease to indicate to the Subsurf modifier that they should be sharpened.
With no points selected (A) in edge or point, select the mode (Ctrl + Tab), hold down Alt on the keyboard, and select and click on one of the edges around the top lip of the cup in order to select all the points in a loop around the top of the mug:
From the 3D View menu, navigate to Mesh | Edges | Edge Crease or press Ctrl + E on the keyboard. Move the mouse pointer up or down in order to increase or decrease the amount of crease applied to the edge until it looks good:
Hold Alt and select and click on one of the edges at the bottom of the cup to loop and select all the points around the bottom of the cup. It may help to switch to the Wireframe mode (Z) or temporarily turn off the Subsuf modifier:
This time, set the crease value by finding the Mean Crease setting in Properties (N). This setting can be any decimal number between 0.0 (off) and 1.0 (maximum). Click on the setting and enter 1, and then press Enter to set the value. Now, the bottom of the cup is flat:

This sort of edge creasing is a powerful way to control the Subsurf modifier. Note that the bottom of the cup is still circular even though the original mesh is an octagon. Subsuf smoothens out the other edges even if it's told to crease others. It's very smart!

Adding a face

Functionally, the design is complete, but it's the little details that really make it. This little octopus would be much cuter with a face:

To start making a cute face, make sure the Edit Mode is off (Tab) and make sure the 3D cursor is at the origin (Shift + C). Now, create a circle (Shift + A) by navigating to Mesh | Circle:
The circle is hidden inside the octopus, so with the circle still selected, switch to the local view (Numpad /). Since this circle will become the face, it's good to name it Face using the same method to rename the object as the one used earlier.
The circle is a flat object that has no face and is just a ring of points and lines. That's easy enough to fix:
Switch to the Edit Mode (Tab). Now, with all the points or edges selected (A) from the 3D View menu, navigate to Mesh | Faces | Make Edge/Face or press F on the keyboard:
The Make Edge/Face command attempts to make a connected face from the selected vertices or lines. It can be quite intelligent, but if the points are not all flat, the edges may twist unexpectedly.
While still in the Edit Mode, switch to the top view (Numpad 7), and with all the points still selected, move (G) them to the left of the green y axis:
Duplicating an object outside of the Edit Mode creates a new object. However, duplicating points in the Edit Mode doesn't technically create a new object. Whatever is selected is duplicated while remaining a part of the same object. Objects in Blender can have many parts to them, all inside the same object.
Duplicate (Shift + D) all the points and place the duplicated points on the opposite side of the green y axis line:
In this way, objects created while in the Edit Mode are just points, lines, and faces added to the existing object, even if they're not connected.
While still in the Edit Mode (making sure the 3D cursor is still at the origin), add (Shift + A) a plane to the face object by navigating to Mesh | Plane:
Move (G) the plane down along the y axis (Y) about 3 units:
Deselect all the points (A) and select the two points at the top of the plane. Then, scale (S) them up about twice in order to create a smiling mouth:
The shapes now look like a face but only in two dimensions. To give it the additional dimension required, select all the points (A twice) and extrude them (E) about 4 or 5 units.
Exit the Edit Mode (Tab). The face template is now complete, and it just needs to be scaled and positioned.
Rotate (R) the face object around the x axis (X) by 90 degrees (90):
Exit the local view (Numpad /). The face is hidden inside the body, so move (G) it in the z and y axes (Shift + X) until it's outside the octopus body:
In front of the Ortho view (NumPad 1), scale the face (S) and move (G) it in the z axis (Z) until it's positioned properly:
In the side Ortho view (Numpad 3), move (G) the face along the y axis (Y) until it's partway into the body:
It may help to use the Wireframe view to ensure that the face is deep enough but not too deep. About four or five small squares (or 0.4 or 0.5 real-world millimeters) is perfect. If the face is too deep, it may cut all the way through into the cup space and may create an overhang problem. The top of the mouth will rely on some bridging during printing, and that's okay.
Now, select the body, and in the Modifier tab, add a Boolean modifier. Change the settings of the Boolean modifier to be a Difference operation with the Face Object.
The effect of this new modifier won't be visible immediately, so select the face object and hide it (H):
Your octopus pencil holder is now complete.
Select the body, and in the Info panel menu (at the top of the screen), navigate to File | Export | Stl (.stl) to view the 3D-print-ready octopus holder. Ensure that you choose a directory where you can find the file later in order to send it to the printer:

Key benefits

Learn how to make complex shapes by editing basic ones

Make printable objects from multiple shapes and parts

Learn how to design from scratch, without a reference to physical objects

Description

This book will cover the very basic but essential techniques you need to model an organic and functional object for 3D printing using Blender. Starting with pen and paper and then moving on to the computer, you will create your first project in Blender, add basic geometric shapes, and use techniques such as extruding and subdividing to transform these shapes into complex meshes. You will learn how modifiers can automatically refine the shape further and combine multiple shapes into a single 3D printable model. By the end of the book, you will have gained enough practical hands-on experience to be able to create a 3D printable object of your choice, which in this case is a 3D print-ready octopus pencil holder.

What you will learn

-- Get to know the guiding principles required to create 3D printer-friendly models

-- Understand material characteristics, printing specifications, tolerances, and design tips

-- Master the art of modifying basic shapes with Blender s powerful editing tools: extrude, loop cuts, and other transformations

-- Learn techniques of editing complex meshes, smoothing, combining shapes, and exporting them into STL files for printing

What do you get with Print?

Instant access to your digital eBook copy whilst your Print order is Shipped

Paperback book shipped to your preferred address

Download this book in EPUB and PDF formats

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Frequently bought together

3D Printing Designs: Fun and Functional Projects

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3D Printing Designs: Design an SD Card Holder

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3D Printing Designs: Octopus Pencil Holder

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Total Mex$ 1,580.97

Peter T. Phelps Jul 08, 2016

I'll start by saying that I am perhaps not the most unbiased reviewer since I have followed Joe Larson (the 3D Printing Professor)'s 3D Printing Workbench YouTube videos (nearly religiously) and own a copy of his 3D Printing Blueprints book. This is a highly affordable lesson into creating organic shapes in Blender (something that can be quite difficult to do in CAD programs). The cute little holder is a great way to get your feet wet in 3D printing design with Blender. I'll be definitely posting pictures of my version of the Octopus Pencil Holder to my website!

Amazon Verified review

Marcus Mar 10, 2016

This short book takes the reader through a simple, fun project as a way to learn to use Blender for 3D printing. As a technical reviewer of the pre-print book who has never used Blender, I learned how to begin a project with a hand drawn sketch, import the image into Blender, and trace over it to create the beginning of a model. Joe takes you meticulously through each step, leaving some room for - and encouraging - customization of the final model that is as cute as it is functional.I liked the project and teaching style. Although the book is short - only one project - it demonstrates the most important design principles of 3D printing for home printers like wall thickness, overhangs, and minimum detail size. I recommend this book to any Blender beginner!

Russell Allen Feb 20, 2019

Excellent book with tons of great information!! Definitely will recommend to others!!! Well written, easy to follow..

R. Garrett Jun 28, 2016

This e-book was apparently a pre-release version of the final publication. This represents chapter 3 of several chapters. There were some issues with using a different version of Blender which is expected so no issues there. The building of the Octopus Pencil Holder went much slower due to a much steeper learning curve due to the first two chapters missing. I had to do much more hunting through menus or even googling for the way to follow the steps of the tutorial. Overall, I guess this forced me to learn more during the process but it is still a bit disappointing that I didn't get what the Author intended to publish.I enjoyed the teaching style of the Author and have watched several of his videos on his YouTube channel which is where I found out about this book. Even though this e-book was far from ideal, I would still consider a future publication if I could first ensure that I wasn't getting a pre-release subset of what was written.I would say if you want to learn Blender, this would be a really good beginners guide if you can get the full e-book or printed book rather than the single chapter I received.

3D Printing Designs: Octopus Pencil Holder: A fast paced guide to designing and printing organic 3D shapes.

What do you get with Print?

3D Printing Designs: Octopus Pencil Holder

Chapter 1. Octopus Pencil Holder

Planning the project

The basic shape

Editing the basic shape

Note

Smoothing the mesh with modifiers

Tip

Bending the tentacles

Tip

Flattening the bottom

Note

Renaming objects

Adding a pencil cup

Note

Adding a face

Finishing touches

Summary

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