I built a twin tower cnc foam cutter many years ago when I was into R/C planes. I cut wings and an occasional fuselage with it. It can do tapers because the towers are each individually driven axes (4 CNC channels)
The cutting software I used (Jedicut) was primarily aimed at wing sections, so it became tricky to cut other shapes. Wings are generally cut from what are called .dat files -- airfoil files with a regular numerical structure.
Lately I've become more interested in possibly doing irregular shaped lost foam patterns, and I've been exploring what I can do with my rig that way. It's not ideal for it, but I've managed to design in old (Google, not Trimble) Sketch-Up, and then massage the design eventually into a .dat file that Jedicut can handle. Kinda convoluted methods to get there. But it worked.
However In researching I came upon this video for a non-wing foam cutter that I think is very cool (possibly slightly flimsy, but the principles are all good). It can't do tapers, being two channel, but an interesting feature is the additional rotary table, which can allow complex 3D shapes.
Anyway thought it might be of interest here.
