I used an ez rivet tool by beadsmith. I had to use a dremel to grind down the die that comes with it until it was in the right shape to not put pressure on the plastic. as far as i know that's the only way to do the arm rivets. or you can modify a pair of grommet pliers to the same effect. the rivets that come with the kit aren't the highest quality, they don't flare that far out, but they work. put too much pressure and you crack the elbows/shoulders. there's a little more info here:
http://www.hisstank.com/forum/g-i-joe-t ... f-kit.htmlAlso, on the snow serps, you have to use a very small gauge drillbit and drill the holes on the arms a little deeper or the rivet flare wont catch right. this was a factory error on the snow serpents. the invasors are easier and you don't have to drill. i'm no expert i just winged it with mine using whatever I had, there's people out there that are better at it than me.