Just swapped the battery in an old beater with a snap on case back.
In the past I've struggled to get them to snap shut.
So I was fumbling around in the garage to find something suitable when it struck me that this might work...
It's actually one of these sealant guns...
It worked a treat !
z
(...& yes I protected the lugs before applying the force)
Ah this is great...I'll certainly be trying it out! Thanks for posting!