The question is where are you going? In the US most states it's perfectly legal to open carry a real weapon even if it's loaded (Carry not brandish). Unloaded it's legal even more places. Not saying it's a good idea for cosplay, just that it's probably legal. Regardless of legality for carrying, even with a fake un-realistic gun, be aware of where you are and who's around. Cops have found more than a handful of real guns which have been painted with an orange tip or even painted so as to replicate a dollar store Nerf gun, so absolutely respect any requests from even the cheapest looking security guard, or if in the US even a citizen as they could be scared of you and armed which is a bad combination.
To directly answer your question, if it's going to go to a con, their rules ought to be sufficient. If you're going to a party/photo shoot in public, just check on local weapons/replica weapons ordinances and be careful what you're doing with them and where. Understand you have more flexibility when in costume and around others dressed likewise. (random citizen isn't going to freak when they see a stormtrooper shooting at a wookie) I'd say you're perfectly fine with the printed Glock so long as you're not at a con and keep it holstered aside from obvious photos. (despite being fake, following real proper gun safety will help stave off problems)
Regardless of what replica weapon you may use, always be aware of others who could perceive it as real, especially law enforcement, and go out of your way to keep them from feeling threatened.