Prop sci-fi guns

One of the most needed props is the sci-fi guns.  I had a look around the internet but some are costly for pre-done guns which look really good however by looking at the shape of these guns it seem to be a nerf gun which kids use by spray painted black and then has added led lights in it, therefore instead of the pre-done sci-fi guns I'll get a normal nerf gun and spray paint it black.

The nerf gun is called "retaliator"

From here I've looked at many tutorials on how to spray paint the gun black to make it look realistic, however the downside to do this is that someone could easily mistake it for a real gun if they are far away and call the police which in turn could have us pointed at with real guns.  Therefore to prevent this I'll need to call the local police department tell them what I'm doing and tell then it's a nerf gun painted black to look realistic

examples below

For people who don't have much gun knowledge they could mistake one for a real gun.