Interesting concept. It holds the coin while you test it's ping.
Coin Ping Tester Prototype by Jobobzig
Printed in PLA. This is still a work in progress. This is the 3rd iteration of the design. So far works with generic rounds, ASEs, Morgans, and generic bars. Design does not include the "smacker" to hit the silver with. More to come when time allows.
www.thingiverse.com