I would need to "order" some 109Fs (I believe that's what was used on the original Zwilling) from someone who has them in abundance in their AO or has some extra loose.
If the Ho-229 were to be done, I would have to build the frame from the ground up, and I have no idea how to go about with that. I have a really nice, big 3-D cut-away view showing the skeleton of the 229 though, so I know how I'd shape it, it's just how would I skin it?
The Zwilling is the more obvious choice. Really there's only a few modifications that I can think of at the moment. Connect the wings with an entirely new wing section, create an elevator, take off the outside stabs/elevators, fill in the canopy and round it forward. I can't tell if the fuselage is longer, but if it is I'm not going to worry about it. It wouldn't be by much.
The paint app, I don't know what I'll do about that yet.
Right now I have $26.

