A while back, I made this grip up for KillSAW One:
Made of Oatey 2-part putty, the methodology is pretty easy to grasp minius words. But it's a bit hard.
Let's say you want a nice CUSHY grip... Check this out:
I suppose you could use the colored material, if you don't mind a funky look...Or intersperse some color into the black, that could be interesting...
Roll it into a ball, and keep rolling until no lines remain in the surface. This way, it will cure all smooth.
Position the extra padding where you need it, and squeeze. Pat down any fingerprints, keep patting, and working the edges so they're smooth in line.
An afternoon or two in a warm dry place, and it's good to go. It's firmly adhered to the fresh paint here, but a bit of cyano may be needed to keep it there.
The blurred sections there?
At the time the pic was snapped, the G36 folding stock I'd added to my:
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M4 was an airsoft anomaly. I wanted to finish the gun before somebody else could do it!