So here’s my situation:
To get through my daily life, My keychain holds four keys plus one USB key.
I have it all mounted in that Aluminum U-Shaped key holder (picture left).

I also have, more by luck than by design, recently acquired an Atwood Keychain tool, pictured on the right.
To find out how this would perform on a keychain, I rummaged around in the cupboard and found three old
keys that don’t have a lock anymore and made up a mock keychain with the Atwood.