I continued to trim the edges of each of the 4 cutouts to get them to the exact dimensions required. Only a couple more to After the initial cut and clamping on a steel edge I use a 3 step process to open up the hole out to the scribe lines. I use the rotary cutter on the dremel at high speed. I use a sanding drum on the dremel to smooth out any high spots and then finally I block sand it was 80 or 60 grit sandpaper wrapped around a piece of wood. Seems to work good with consistent results.
Step 3 in the process - sanding against the steel edge
