So I had an idea when reading second DD and I will expain it now.
So the idea I got for me it's intresting. Maybe minor nations and majors if they desire can design their own armored units.
How would it work(in my mind it seems perfect but you know how it is) is that you research like let's say panzer 2 and then you research upgrades for it but you still know and can build older tanks. So you have an button, fund a team to design a machine for you. Only thing you do is press the button. It would use all your current techs on that tank type and make up the best mix. Gun size and track type, engine etc. The AI will do tests and use resources avaible to devlop the best tank they can. Of course you can't let them develop perfect tank.
So the idea I got for me it's intresting. Maybe minor nations and majors if they desire can design their own armored units.
How would it work(in my mind it seems perfect but you know how it is) is that you research like let's say panzer 2 and then you research upgrades for it but you still know and can build older tanks. So you have an button, fund a team to design a machine for you. Only thing you do is press the button. It would use all your current techs on that tank type and make up the best mix. Gun size and track type, engine etc. The AI will do tests and use resources avaible to devlop the best tank they can. Of course you can't let them develop perfect tank.