Cartels can submit two private, one public design a year. Why not let the owner pay to increase that?

CARTEL WYRMWOOD BUY SUBMISSION SLOT:
For (10/15/20) credits, you can buy another private submission for this cartel.
Possibly another public slot for some other price. This addition is permanent.

Obviously, you wouldn't want to buy slots for city/commune cartel. But I know Sthai owns quite a few, as does Kharaen, and they may or may not want to add to their submited designs.

I know I would.

I approve.

I also want the ability to trade actual recipes/designs, not just sketches.

How does that work?

I'm still wanting my onyx cherub bed in Wyrmwood.

You can transfer designs from one cartel to another but I think you have to be (at least temporarily) trademaster of both to do it.