No artist? No problem. I've been working around a lack of artistic ability for years by using 3d-modeling software. There are loads of tutorials for the two programs mentioned here and as a bonus, this is all completely free.
- photo editor (photoshop-ish or a paint program) where you design your components before printing
- 3d modeling software: here are a couple I recommend based on your needs and skill level
Blender is for the heavier, all-in modeler. This is a catch-all modeler for animating movies, making video games, or basic model shots like in this video - http://www.blender.org
Anim8or is my favorite for the sake of its simplicity. I usually start here even if I end up exporting to the beefier modelers - http://www.anim8or.com