You would be better off modifying your gun to take a suppressor than making one yourself. I assume it is a Taurus 24/7 or similar. I had one when i first started playing and drilled out the end of the slide (or what would be the slide)
to fit a socom suppressor, like the one used on a MK 23. This type of suppressor threads into the barrel rather than the barrel threading into the it ( male-female as opposed to female-male).
Alternatley, you could build a Threaded sleeve which you could epoxy to the end of the gun to fit a regular AEG suppressor to. Keep in mind you will need one with positive threads or an adapter since you do not likely have access to a 14mm negative die to thread your sleeve on your gun.
Oh and make sure the outside diameter of the threads on the sleeve is 14mm as well.
Travis R. (aka Trapper)
Canadian Airsoft Marines. Field owner