The weight of the airframe (before adding the landing gear, motors, servos, etc.) is supposed to be 1160g, and all-up weight with batteries should be around 2kg. Most of the structure is only one layer thick (about 1/2 mm). At 1160g that means the cost of material is about $40.
I am printing with PLA, a kind of plastic. Downside is that it can get soft if out in the sun too much but they say that ABS is too brittle.
See
https://3dlabprint.com/shop/lockheed-p-38-lightning/ for more.
I can only imagine how many pieces it will end up in after a crash, so questionable as to whether this approach is really practical, but it is interesting.