3D Printing Blueprints: Using the free open-source Blender software, anyone can design models for 3D printing. Fantastic fun and a great experience whether or not you have a 3D printer, this book is a crash course in the new technology.

3D printing has come a long way in terms of technology and cost allowing home 3D printers to be a reality. In this process there have been choices that will limit what can be printed. Seeing a 3D printer in action is the best way to learn about the process. Fortunately there are many 3D printing time lapse videos online of printers in action that can be found with a simple search.

3D printers build an object layer-by-layer from the bottom to the top. Plastic filament is heated and extruded, and each layer is built upon the last one. Usually the outside of the object is drawn and sometimes additional shells are added for strength. Then the inside is usually filled with a lattice to save plastic and provide some support for higher layers, however the inside is mostly air. This continues until the object is complete as shown in the following screenshot:

Because of this layer-by-layer process, if a design is made so that any part has nothing underneath it, dangling in the air, then the printer will still extrude some plastic to try to print the part which will just dangle from the nozzle and be dragged into the next area where it will build up an ugly mess and ruin the print:

One way of fixing the dangling object problem is to configure the preparing software to build the model "with supports". This means the slicer will automatically build a support lattice of plastic, up to the dangling part so that it has something to print on. Higher-end printers can actually print with a different material that can be dissolved away, but so far most home printers only use break-away supports. Either way after the print is complete it is left to the user to clean up this support material to extract the desired part.

While supports do allow the creation of objects that would be impossible any other way, the supports themselves are a waste of material and often don't remove cleanly leading to a messy bottom surface where they contact the print. If a part is designed needing supports that are hard to remove, such as if they're internal and partially obscured, it can be difficult and frustrating to completely remove the support material (this can be true for even the higher-end 3D printers). The process of removing it may actually damage the print.

It is possible and very easy with just the slightest application of cleverness to make designs that are printable without the need for any supports. So the blueprints in this book focus on making designs that print without supports. The limitations imposed by this demands just a little more effort but allow for the teaching of principles that are generally good to know.

Some models of Makerbot and other 3D printers have the ability to print in multiple colors at once using two different extruder heads feeding plastic from two different spools. There are some fun prints that come from this process. But as most Makerbots and other brands of home 3D printers do not have dual extruders at this time this book will not explore this process in detail. The basic idea of the process is creating two files that are aligned to print in the same space and combining them in the slicer.

When designing for supportless printing the rules are simple: Y prints, H prints okay, T does not print well.

Branching out with overhangs

It is possible to have the current layer slightly larger than the previous layer provided the overhang is not more than 45 degrees. This is because the current layer will have enough of the previous layer to stick to. Hence a shape like the capital letter Y will successfully print standing up.

However, if the overhang is too great or too abrupt the new layer will droop causing a print fail, hence a shape like the capital letter T does not print. (If the T is serif and thus has downward dangling bits, it will fail even worse, as illustrated previously.) So it is important to try to keep overhangs within a 45 degree cone as they go upwards.

The main window where things will be happening is the 3D View panel. The largest portion of the 3D view consists of the viewport where most of the work will take place.

On the left-hand side of the 3D View panel is a tool bar that consists of tools relevant to the selection and mode. If the tool bar is ever not visible it can be revealed (or hidden again) by pressing T or by clicking on the plus icon on the right-hand side that will appear when the toolbar is hidden. The specific tools in this bar will be explored as they are needed in the projects.

There is another plus icon on the right that will bring up the viewport properties with properties relevant to the current selection or the viewport. This can also be revealed or hidden by pressing the N key. Again, the specifics will be explored further as needed.

At the bottom of the 3D View panel is the 3D view menu bar with additional options followed by menus and icons related to editing and views. Hovering the mouse over each button will show what they are for.

The Outliner panel contains a hieratical view of all the objects in the scene. Each object can be selected by clicking on their name or the object can be hidden, locked, or excluded from rendering.

The Properties panel is broken up into many tabs indicated by small icons. Hovering over the icons will show the name of the tab. For modeling the two tabs that will be used the most are the object and modifier tabs. Specific exploration of the tools contained therein will be done as needed.

On the top of the Blender windows is the Info panel. On the left-hand side of the Info panel there is an easy to navigate menu similar to the menu in most applications. This menu can be collapsed by clicking on the + button next to it and expanded by clicking the same. On the far right of the Info panel there is data about the current scene. If the data cannot be seen, hover the mouse over the panel, and use the middle scroll wheel or click-and-hold the middle mouse button (pressing the wheel like a button) and moving the mouse to pan the panel until the desired data is visible.

The Timeline panel is only relevant to doing animation and can be effectively ignored or collapsed for the purposes of this book.

While all of Blender's functions are available from buttons and menus on the screen, typical Blender users rely heavily on hotkeys and shortcuts. Already the T and N keys have been discussed to bring up or collapse the Tools and Properties tabs in the 3D view. For this reason it is recommended that to use Blender have one hand on the mouse and the other hand on the keyboard at all times. This tends to be a common stance for many people but is mentioned for the few for whom learning this will be of great help.

One of Blender's strengths is its customizability. Almost every feature from the look and color, right down to the keystrokes and hotkeys are used for every action in Blender. Customization is accomplished in the Properties menu accessed from the File | User Preferences menu.

The buttons across the top, switch to the various categories. Each category is packed with options. A full exploration of these options is beyond the scope of this book but the reader is encouraged to explore these options and make Blender their own.

For instance if the reader is using a setup where a middle mouse button is unavailable, Blender contains an option to emulate the middle mouse button by pressing Alt along with left-click. Other systems may require other accommodations many of which are available in this menu.

Mac OSX users require special consideration. Blender is made for a three button mouse. If a single button mouse is all that is available, click when the instructions say Left-Mouse Button, use Alt with click for Middle-Mouse Button, and press command with click for Right-Mouse Button.

Blender employs some conventions that are unique to its environment and as such getting acquainted with its most common quirks early can avoid frustration.

First and perhaps most importantly, Ctrl + Z for undo works in Blender will undo a multitude of mistakes. Undo in Blender remembers many past steps allowing backing up to a point before a grievous error was made. Remembering this when following along with the blueprints that follow will save the reader much frustration.

Next, the location of the mouse pointer is important when using hotkeys. For example the T and N keys for the Tools and Properties tabs do not bring up those tabs if the mouse pointer is not hovering over the 3D View. If the mouse is hovering over a different panel the reaction could be unpredictable. Pressing the A key with the mouse over the 3D View will toggle selection of all objects in the scene. Pressing the A key with the mouse over the Object Tools tab will collapse the expandable menu hiding all the options of that menu.

Blender uses the right-click on the mouse to select objects by default. This is perhaps the most counter intuitive thing for first time users, particularly because it will be encountered so frequently. But not everything has been swapped, just object selection. This behavior can of course be customized. If the reader would like to customize selection to the left mouse button then it is left to them to adjust the instructions accordingly.

Finally, the relation of Blender units to real life units is not by default defined in Blender. Generally it is just easier to remember that 1 grid point will translate to 1 millimeter in the printed object. As the scale is increased Blender inserts darker grid lines every 10 grid lines by default which correlate to centimeters. So the default cube in the default scene would measure 2 mm on each side, which is less than 1/10 of an inch, which is very small.

In the projects in this book, when a new idea is introduced it will first be introduced with detailed steps. Once a process is taught the next time the name of the operation and the shortcut for that process will be all that is given. For instance the first time the scale operation is introduced in Chapter 2, Mini-mug, the process is laid out including how to start, modify, and end the operation, but later an instruction like "scale (S) the object" is all that will be given. This does not mean that the keyboard shortcuts are the only way to do an operation but they are often the preferred method for experienced Blender users. The reader is free to accomplish the operation in any way that is comfortable for them.