Say, if I made a toy replica of a Spiral Knights weapon and attempted to sell it for irl money, would I possibly get sued? The reason I'm asking is because in this hypothetical situation I'm taking the idea for the weapon from OOO's game but I'm putting my own effort into it.
Question about fanmade merchandise
so you want to steal someone else's work and sell it for money? Sounds like a plan. (copying someone's in-game art is copyright infringement)
Anyways, the answer to your actual questions (the outcome, not the legality) it really boils down to how you sell any items. If you sold them in very small quantities to your friends, then OOO would be none the wiser and most companies wouldn't care (I don't know if OOO would care). If you sold them on e-bay/amazon or some other mass distribution, then I'm almost 100% positive you'd get a cease and desist letter and that might get followed up by a lawsuit.
Haha I'm not good enough to make a weapon replica, this is a purely hypothetical situation.
First things first: Gotta get permission from OOO and Sega(probably not Sega but better safe than sorry). Tell them what you are doing and how you are selling it. They will probably respond with either:
1. No
2. Yes, but a share of profits due to the design
3. Entirely Yes. No need to share profits(I doubt it)
They probably will add terms and conditions. Oh look I got trolled in this thread..woo..
You know... noone needs to know... but you just 'almost' confessed to it.