So basically a rivet is a round peice of metal with a raised, circular part at the end? And to "rivet" a rivet, is basically to compress it so it fills the (For example, trunnion) hole to be riveted?

And about riveting tools-what can I use? I've got a bolt cutter, I've heard that some people use those in riveting their AKs together.

Check out HC Pookies website (I don't know the address offhand).  He has a lot of good information.  RTC

pookieweb.dyndns.org:61129/AK/rivet/boltcutters/boltcutter.htm

Who's rivets should I get for a Romanian kit? I've heard the Tapco rivets are too small. Is that true?

Get the Bulgarians from ak-builder.com

A rivet has a mushroom head on one end.  When you "rivet" it, you form a mushroom head on the other end.  Supposedly as a result of the compression the shaft will expand out and press against the trunnion hole.
Tapco rivets are too thin.  Several people resell Tapco rivets, DPH and Midwest Armory are two I believe.  You can tell because they use the same picture as Tapco.  You can get good rivets from the EE.  low_lead was selling them.  I don't know how many he has left.  They are leftovers from a rivet group buy.
Bolt cutters require extensive modification to use.  SOCANDYMAN has made a post describing what he did along with pics.

fadedsun,
Are you a deputy in Uvalde County?

Quoted: fadedsun, Are you a deputy in Uvalde County?

Where's Uvalde County?

No, no LEO here. Call me back in a few years and I can say yes...

I went to high school with a 'Ben' who is an LEO in Uvalde Co, down in the southwest.  I'm thinking abot going that route myself.