Like all my stuff, this project is easy and cheap. And works.
This particular tool is to make 6mm diameter rivets, but you can scale it up or down.
Drill (preferably a pillar drill, but any drill will do if you have a steady hand)
Metal drill bit slightly larger than the rivet diameter you want to make. I used 6.5mm. 6.2 would have been better.
Head of a cheap club hammer (mine was from the pound store)
For the rivets
6mm mild steel rod
blowtorch or forge
Step 1: You Do the Maths
Figure out how long you want the shaft of your rivets. In my case I needed the rivet shaft to be 10mm.
Figure out the required rivet head size. The normal calculation for a rivet head is 1.5 x the diameter. For our 6 mm rivet this would be 9mm (duh).
Add these together and that gives us the depth of the main hole.
Step 2: This Is Your Pilot
Drill a pilot hole all the way through the hammer, I mean 'rivet header tool'. The reason for this hole will become apparent later.
Step 3: You Know the Drill
Using the pilot hole, drill the main hole to the determined depth (19mm here). Make sure you are as accurate as you can manage. If your drill has a depth guide, nice. If it doesn't you can mark the drill bit with masking tape.
If you're not used to drilling metal, the key things are to use a decent drill bit, drill slowly and to put a small drop of oil on the metal you are drilling. Otherwise the heat from friction can cause the very spot you are drilling to harden and make it impossible to drill. Not so good...
Step 4: Cut a Rivet Blank
Cut a rivet blank from the 6mm rod. This needs to be the depth of the hole (19mm) plus 9mm for the head.
Step 5: Make a Rivet
Pop the blank in your new shiny tool. It should protrude by about 9mm. A little bit either way shouldn't matter too much.
Now heat the rivet until it's hot hot hot. You can do this in a forge or with a blowtorch. If you are using a blowtorch you can leave the rivet in the tool, as the rivet will heat much quicker than the tool.
Now whack it until you have a rivet head. Actually, hit it reasonably gently to get it started, you want it to mushroom rather than bend over. This may be slightly easier if your hammer has a ball end.
There are various shapes rivet head you can go for; round, flat, button, square. The example here is slightly flared as it suits the project I'm working on. As long as the head is wider than the shaft it will work.
Step 6: Now What Was That Pilot Hole for Laurence?
Chances are, the rivet won't want to come out of the tool of it's own accord as the heat and hammering has made it expand.
Turn the tool over, pop in an old drill bit or thin punch, hammer it gently to help pop the rivet out.
Step 7: Admire Your Rivet
Step 8: What About the Other End?
Poke your rivet through the thing you want to rivet. 9mm should protrude. Heat it with a blowtorch. Whack it to shape the head as before. Done.