Paperweights used to hold down Art, Posters, or Maps for framing My local frame shop uses weighted leather discs to lay prints out flat.
These paper weights are essential for keeping rolled posters flat on a table. I can also see them being used in the map / cartography hobby. They're soft, so as not to damage the paper, small enough to cover only the corners, but also heavy enough to hold down a rolled poster and not move.
I'd like to buy some for framing at home, but I'm finding these items to be surprisingly difficult to find. I can find almost no pictures of them in use. The ones I can find seem overly expensive or rare.
What are these items called in the framing world?
Where do frame shops purchase these paper weights? Are they available at craft stores?

I might describe them as paper weights, bean bags, sand bags, shot bags, weighted leather disks, etc. But there are not many results for any of these terms. It seems like these should be a common item.
Weight bags/Paper weights to hold down art
as pkamb said in the commments.  Also, I searched "paperweights to hold down art" and the ones you're looking for are there. Take a look at it, that's what you're looking for.