When the RV-12 originally was developed the build process called for a PRP-26A tight space pop riveter. This tool was used to pull pop rivets that were too close to other structure to allow room for the tool to pull the rivet. Emhart, the manufacturer of the PRP-26A riveter, "retooled" for this riveter. When they did the new tooling cost allocation drove the price of this hand riveter to about $150, an outrageous price.
Because of this many builders have used many different ideas to come up with a way to pull these rivets. The best resource for tight space rivet tool is this EAA video:
Our RV-12 kit includes a pop riveter that can be modified (ground off) to remove much of the nose piece to allow for meeting most of the tight space requirements. This has worked well for our builders. We are continuously looking for alternates to improve the building process for our RV-12 builders.
Let us know ifyou have come up with any better ideas on the RV-12. Keep up the great building!