I found a site called PlanePrint.com that has plans you can use on a 3D printer to make airplanes. It is interesting to see how heavy each of the designs is and the wingloading. There is a video of someone printing and assembling one of these planes. Also another print and assemble video where it took 72 hours to print.
It seems like more work than our "CNC to cut foam frame and then cover" approach. The 3D printer makes lots of small parts that then have to be put together.
I hope to build up a collection of plans that people can use on a CNC to cut foam for making an airplane. I think we can make planes that are lighter and more durable with our approach but we will have to get some flying before we can say for sure.