I had heard so much about these clear plastic curved blocks for stamping that I had to try them. They ARE everything they are cracked up to be. They give a perfect imprint every time if you have inked the stamp well. It even works with the PTI Boards and Beams house that everyone has so much trouble with. I got mine on sale for 25% off and could not pass them up.
I think the little one will be pretty useless. It is too hard to ink without getting ink on the "rails", but the big ones work very well and it is my bigger stamps that I have an issue with. The back of the packaging for the blocks tells how these can be used with bare rubber. I am thinking double sided tape would work too.
I understand All That Scraps carries these blocks.