The first of my scratch built styrene parts is now complete. The first part I tackled was the front coin return. Looking at the blueprints from the R2 builders club yahoo group, this piece looked like it would be pretty easy. All straight edges were key. The hardest part was the thin section at the bottom. This part was so thin that when I tried to cut out the center, it split. I had to remake that part by tracing the broken one. Most of the cuts can be snapped off, but the center cutout needs to be cut clean.
I cut all the parts without a 1:1 blueprint. If I had a full scale drawing of the part, cutting would have been much easier. Instead, I used a digital caliper to help me get the correct dimensions. Had I not used the caliper, converting the dimension form decimals to fractions would have required way too much time and effort; the conversion also is not very accurate.
The last photo posted here is a shot of one of the coin returns from a film-used droid. Notice just how rough they are. Scratch built returns will definitely look as good or better.