[@ACHTUNG]: Oh crap, I forgot to talk about this. I had it all written up and everything. rip.
Well, better late than never.

400m/ half a mile is still HUGE. Like... HUGE. Tone that down by at LEAST 1/8.
Complexity... 'kay, being able to make things like an aircraft? Yeahno. That needs to be toned down as well. Nothing quite as large and complex as that. Like, a car is fine, but not a commercial airline or something.
Physical limits A-OK.
Being able to go into concepts... That's a bit... Dangerous to deal with. Remove... I think.
Limit quantity depending on complexity. Gate it based on that.
Creation thereof... I think that seems kinda reasonable...?

So yeah, my input.