I use the Kadomaru Pro Corner Cutter to round the corners on gimmicked playing cards I make to perform magic tricks. The cutter can also be used to round the corners of postcards, business cards, photos, and any other paper or card stock (as long as it isn’t too thick – it resists when I try to cut two playing cards at the same time).

It has three slots, labeled S (3 mm), M (5 mm), and L (8 mm). The 3mm is perfect for Bicycle playing cards. To use it, insert the corner of the card into the slot until it stops, then press down on the handle until it clicks. The cuts are very clean.

Submitted to Cool Tools by Mark Frauenfelder