You should consider posting this in the "Show and Tell" thread about homemade tools - https://pinside.com/pinball/forum/topic/show-and-tell-your-diy-homemade-tools

I think a lot of people there would find this interesting. I certainly never thought of this.

For non circular cutouts, you could 3D print a template for a router with a bushing in it. Then you can get rear creative with shapes and they are repeatable.

For some reason step bits are expensive anywhere that isn't Harbor Freight.

I am assuming that you will be cnc'ing your future playfields and the plastic on the same machine. You should add in some registration holes. Maybe down under the apron and then near the top in a place where they wont be seen. Use the same diameter holes in the wood and in the plastic, say 1/4". Then use 1/4" pegs (router bits, dowels, drill bits, ect) to go through both sets of holes to help align everything.