I bought this 1/8 pop rivet dimpler from Avery's to dimple the stainless firewall for the top forward frame. It does a nice job. I had the 3/32 set already. This is really a must have tool also.
Look how big the nails are compared to the #40 dimpler.
And you don't pull this until it breaks. You just add enough pressure to close the dimple dies and it makes a great #30 dimple.