Modifying the final composition with new SketchUp output
My final image is shown here. It's not great, mostly because the textures weren't great in the first place, but it is much better than before. Repeating mechanical textures, like the ones shown in the following image, look really fake in the Dennis Technique. I also don't feel the lines are sketchy enough, and I may have been too heavy-handed with the main colored area. So, what can I do about it? Lots!
Using layer masks has allowed you to apply lots of effects to the final image while not damaging the underlying layers. So, you can just go in and swap them with some better ones! You can also go back to any of the layer masks and reveal more or less of each layer, neatening things up as you feel the need. Nothing is ever lost.
Modifying the Dennis Technique
This can be challenging because it's open ended. However, you're up to it. So experiment!
Go back to your SketchUp model and try out another sketchy-lines style. Choose a really scruffy...