Where to get motor plate rivets?

[Deadeye]

Doing a pillar drill restoration and managed to lose one of the teeny rivets that holds the info plate on the motor. It pinged off and is lost to science.
What are they called, where can I buy them and how are they measured?
Thanks!!

 

[deema]

Hammer rivets, just google, plenty on eBay for instance

 

[Deadeye]

Great - thank you!