If you happened to notice on this post from last week I put up metal strips for hanging work prints (22 inches long, $1 each from Ikea, but that's a different endorsement). The ugly black and white checker magnets were the best I found at the time and weren't able to hold anything larger than 8 1/2 x 11. I found some chrome spring clip magnets at an office supply place but they leave marks and are about 1 1/2 inch square.
I was looking on the internet at something else (my usual source for amazing finds) and came across the peg mighties. They arrived today and we have a winner folks! Each one of the chromed (i.e. non marking) magnets is about the size of a large grain of rice (5/32 inch) but two easily hold a large (26 x 24) lightjet print nearly invisibly. One holds an 8 x 10.
If you need magnets these are truly amazing. I have the cubes and the all mighty coming. I'm relieved I got the pegs and cubes because I fear I wouldn't be able to pluck off the small rounds.
I love it when something works the way they say it will. It seems to be getting more and more rare.