I'm glad it worked for you.
It seems that often modelers look for fancy tools that they might think will be faster or better (dang the expense), but they forget the old tried and true methods.
I often need to cut plastic disks of various sizes. I'll pull out my old trusty bow compass (remember those from high school geometry?) with two pin points. I'll set in the desired radius and swing the circle on some Evergreen sheet stock. One or two passes will cut thin stock. Thicker stock may take a bit more effort: score snap, sand.
Remember the KISS principle - Keep It Simple, Stupid.