Contributors aren't a bad idea, no. A system just has to be set up for it which I'm guessing is why it hasn't happened yet. As for rewarding people with stuff, I'm fine with everything besides exclusive things. If 5 people contribute [something] and then those 5 people get 5 new and unique codeguns with new and unique cool effects added to the game, that's 5 new and unique guns that are effectively dead content.
The way I'd like it done (same with SRPs, frankly) is if there's an original version, and an open-use version. Contributor gets to have the original item, with its chosen name, visuals, stats, whatever, and everyone else gets an altered version. New name, new infocard (also referencing the original its based on), maybe slightly different stats and the effect for it adjusted slightly so it's not a carbon copy. That way people get exclusivity without the effort put into the item going to waste.
Didn't we have something similar to this in the past anyway? I remember people being paid billions for making trailers for Discovery. As of 7/5/2022 nobody is stopping people from mass producing effects for engines, thrusters, guns, ship models, whatever. If some guy comes into my DMs with a finished entry for a codegun with an infocard and effect ready I'll put it in the game. Don't see why the dude can't get like 250-500 million, some unique visual effect of his choosing on some ship he owns or a set of special event guns for it if it's great quality.