You can find places online (for example Shapeways & iMaterialize) that will "print" the parts for you.
What I was trying to say a few posts back is that the entire economic landscape of small scale manufacturing is changing, not solely because of these on-demand manufacturing technologies, but because of the influx of information technologies in general. It means the economics of distribution changes, it means product design can be crowd sourced, it means easy access to global markets. All of these things bode well for niche products like esoteric models of obscure WWI aircraft.
Yes, as someone pointed out, these kits will not design themselves, but go spend ten minutes in the nutball hobby flight sim world and you will quickly discover there are tons of highly skilled 3D artists out there designing extremely detailed and accurate models of aircraft for free or next to nothing, solely to advance their hobby. Yes, the end application is different and specialized in its own way, but the basic skill set is the same. I've done both modeling for SLA production (3D printing) and for computer games, I'd say the latter is much harder because the limitations are so much stricter.