I'm guessing that most of us remember Sandvik sintered metal sanding plates? I've had one for nearly forty years and it still works fine, but have always kept an eye open for another one. Last week I found a mini version on eBay, the NT Sander from Japan. It's made from 0.2mm stainless steel and about the size of a credit card. It looks as though the "pimples" are laser etched. It's flexible but comes with a sheet of double sided tape so it can be attached to a block.
I bought the fine grade which is perfect for removing grain, raised after varnishing small parts.
I doubt it will last forty years like the Sandvik, but it's a lovely piece of kit.