Hi Mark. Thanks for the feedback. Sometimes you get lucky and an idea works out OK on the first swing.
The way I made this was to sketch out the idea on .2 plastic, add straight guide pieces of .2 plastic around the perimeter and the inside angle piece of one half of the sketch, drilled holes at each corner. I took that template and placed it on the .2 plastic sheet that would become the outer skin. I drilled out all the holes on one side of the outer skin piece, flipped the template over and drilled out the other side so the 2 sides would match, and "connected the dots" with a straight edge and #11 blade. A little filing and sanding and I glued it to a second .2 plastic sheet to create the indentions.