Rebuilding '69 Chevy vent window
 

I am refurbishing the vent window on my '69 1/2 ton. I am working on replacing the division bar w/felt and have run into a problem. This piece is riveted to the vent window and the rivets are supposed to be flat. Possibly requires a special tool to do this. Only problem is that I have no clue what the tool is actually called or looks like and the Napa store here has no clue either.
So, anybody have any suggestions on what the tool might be or how to go about flattening these rivets without screwing up the piece?
This is my last step of replacing all the rubbers and felt on the truck.
:confused: