Penny sliders anyone?  These are dies designed for slider cards.  Add a sliding sentiment, a little train, animal or maybe a baseball and you are set to go.  Of course, the designs may also work with another idea you might be thinking of...   These high quality steel dies are compatible with most die-cutting machines.
Die measurements as follows:
Large full semicircle:  3.25x1.78 inch
Smallest shallow semicircle:  1.75x 0.5 inch
Large full semicircle:  3.75x1 inch