This is what I had in mind. The little lock on top hinges over to lock the prongs apart. when you need to take the shell off, you can flick the lock back with a fingernail or something, and the prongs can come together so the shell can come off.
It would be nice to have one-piece posts- pins can deffo be a pain when they jump off and get lost in the grass at the most critical times...
What do you think?
Cheers,
Ty