RE: smallest 3D plane you know of?
My plane may not be the smallest but it sure does fly with the best versatility of any plane I ever flew before! I took the free plans for the Mini 3DX and scaled them down to 78%, this gave a wing span of 25". This plane absolutely rocks with a 3S lipo outdoors, extremely fast roll rate when you want it, does every trick in the book. For indoor flight switch over to a 2S pack and it becomes a much more docile but fully functioned 3D. The Mini 3DX in original form with the 32 inch wings is a very floaty slow flyer but downsize it a couple of steps and it becomes a rocket with the 3s or back to semi-floaty with the 2s, I guess that slight wing loading difference realy makes a difference.
My flying club buddies, don't have a clue about me flying the little bird, it should surprize them how my flying skills have improved over just one winter.