posted a while back about wanting to make my own gun for this and have made a start on one. So far I'm happy with the progress. Painted up like this it will make a satisfactory vaguely sci-fi looking pistol that can be used in any game where you're not fussed about having replica kit.
At this point I've got a trigger, reload switch, battery compartment, emitter and muzzle flash LED ready to go which is getting it down to sticking an Arduino in there and making it work.
However I'm going to pause for a bit. I painted it last night and while I like the silver finish it's still slightly tacky. I've had this with NERF guns before, the paint seems to take ages to dry, which must be related to the solvent getting into the plastic of the body. I know from experience handling it too much will mess it up so I'll leave it a while longer to dry.
This leaves me time to sort other things on my to-do list for it like ordering some of those AAA Li-ion batteries, sorting out a suitably compact sounder, coming up with where to mount an on/off switch, making a status indicator which may just be an RGB LED and building the 'gun board'. The latter is actually the fairly easy bit.
I'd love to leave the USB programming port for the Arduino accessible if I can and maybe have a 7-segment or matrix display but I suspect the latter is stupid 'feature creep' that will drag the project out and make it unnecessarily complex.