've built many boards using pop rivets...

make sure you use plain steel rivets, (don't use aluminum or
stainless steel.. won't solder). 
knock the "nailhead" out after you pop 'em in... (they come out real
easy).   the 1/8" long ones...     I've been looking for ways to add a few eyelets to a stuffed
Fender eyelet board without having to disconnect all or most of the
wiring. The idea of using steel rivets sounds like a winner. So how
much clearance do you need under the top board to punch the rivet
"nails" through?

Steve Ahola

P.S. For making new eyelet boards I've been using an unpowered
8" drill press with the staking kit from Mouser. Just pull the lever
down slowly and the eyelets are set perfectly everytime... BTW
Bruce Collins had mentioned also using larger 3/16" brass eyelets
(available from your local fabric store... when you are shopping for
some nice material and patterns for a new dress!     ) These
larger eyelets are good when you are trying to connect more than 3
or 4 leads. 

I use Airbrake ferrules for truck air brake systems 
they are machined brass and come in different sizes from 1/8th up.
I also have used bushings designed for model airplanes, available at
your local hobby shop. I made a little press to press them in that
uses a tiny C-clamp for pressure so there is no shock or jolt....this
especially important in an already existing amp....at least I think it is.
The air brake ferrules look great! 

Peter S