Back again to see another instructable?) Anyway, there is nothing hard and special, this are just plastic Mausers in SW style
Materials you need:
1. Something what looks like (1.1 cone, 1.2 tube)
3. Different things from.. Different things (This is scratch build, what have you expected?)
4. Mauser's copy
5. Telephone wire
Step 1: Craft!
This is the only step, you just need to craft blaster using everything you see;) I've used packages out of nozzles for the engraver, pieces of crane.. I don't know what can i write, you just need to use you imagination.
Good luck in your craft ;)