Just a quick word for those of you who wish to make sketches of your next mod. I'd suggest using a program called Sketchup. It's truly amazing in the way it works compared to other programs (rhino, autocad, 3dsm, etc.) It allows the complete novice to create intricate designs/cuts/shapes with ease.
I rate myself as pretty advanced with 3dsm, master of rhino, and proficient in autocad and I highly recommend using sketchup for its pure modeling speed and ease of use.
Check it out by downloading the fully functional timed trial here:
http://www.sketchup.com/