I'll second that. I'd do an image search for the model of blaster you want to replicate. You are likely to find 3D printers. If they only do STL files you can have anything printed at https://www.shapeways.com/ if you don't have a local printer.

For example from my search I found some products here https://www.etsy.com/market/blaster_stl

Looks like this guy makes the barrel shroud you are probably looking for

http://www.tomspinadesigns.com/custom-sculpture/star-wars-licensed-characters/paintball-blaster-props-star-wars-show/

Find a prop to cut up and glue on
https://www.amazon.com/Custom-Designed-DC-15s-Blaster-Functioning/dp/B07NSFNLSB