This polygon mask was made on a Shopbot CNC router.
THIS INSTRUCTABLE WAS MADE @ TechShop Detroit
Step 1: TAKE FACIAL MEASUREMENTS
TAKE MEASUREMENTS, do some crazy CAD sweeps or make it manually with extrusions. If you want this polygon shape with three planes: I used 2 datum planes an inch apart. Then on the bottom plane I sketched a 6 side shape. On the datum plane above that one, offset the sketch smaller and sweep the two together,do this again for a 3rd plane even smaller and sweep again. Keeping in mind the three inches, leave about in inch for the nose.
leave tabs on two arbitrary locations so that the mask can be supported while cutting.
Step 2: CUTTING ON THE ROUTER
I took a sheet of DOW foamboard and cut it down into 10 x 14 inch sheets and I doubled stacked them by gluing them with spray adhesive. If you do use spray adhesive, just spray one layer on each side of the foam board and clamp it, but make sure you you don't put too much spray (youll be able to see it) because it will melt the foam and you will get uneven surfaces AND one half may fall off while cutting : which is what happened to me haha! I used a 3inch endmill Rapidkut because the sheets were 1.5 inches each which made a thickness of 3 for my stock. Also make sure to cut them on a band saw to insure the best zeroing since it is a double sided cut.
I also used a sacricicial half inch mdf underneath while cutting incase I crash the spindle(which didnt happen). I also used the spray glue to stabilize the foam to the sacrificial board. Ultimately using the vacuum pressure of the shopbot alpha to keep it clamped to the shopbot board. Using Cut 3D, I skipped the rough cut and went straight for the finishing cut because foam is supersoft and cuts like butter. I used a spindle speed of 10,000 RPM, 10 inches/sec, and plunge rate of 5ips. I also used a 45 degree raster.
once you cut one side, flip it over and make a new toolpath for the backside.
It really doesnt matter what size stock you use, as long as you zero from the middle using a symmetrical 4 sided shape.
the whole mask took about twenty minutes to cut
Step 3: Finishing
since I only wanted to do one pass with one bit, I figured that I would cut the eyes and mouth out manually with a knife. also cutting the tabs off with a knife.. Poked some holes in the sides and used some rubber bands.