Router - Cutting Thin Sheet Clamping??

I am building my first CNC wood router mainly for cutting model
aircraft parts out of 4mm coroplast and thin Balsa Wood (1/16 to
1/8" Thk) and maybe upto 1/4" Ply.

I plan on a vacuum hold down system.

My question is how can I fixture this material so that I can cut
through the entire thickness without destroying my table? I am sure
there are lots of people doing this.

Thanks for any suggestions.