Fascinating project! I may have to steal the idea...
Unfortunately I don't know of any such architectural kits (and I have trawled for 28mm Japanese building kits for years now and have a pretty comprehensive collection), so that would seem to leave one of three options: 1) find a friend who does have a 3D printer, or else make one; 2) learn to scratchbuild; or 3) commission something from someone. Most of these will cost time and/or money but such is this hobby I suppose!