I'm overhauling a 6x9 roll film holder. Has anyone removed the 11 rivets that hold these together? Do you drill them out, or press them out? Just wondering.

I don't know much about your holder, but I have removed many rivets in my other repairs.
The safest way - so you don't enlarge or distort the material - is to gently grind the top hat part of the rivet (not the part that has been flared) and push it out.
You can use a Dremmel with a 1/2 inch fine stone or a diamond impregnated bit.
Good luck
David Gaon