My original Key Remotes for my car alarm were almost completely gone so I designed a new enclosure and reused the electronics and key pads.
To be able to change batteries top and bottom half can easily be separated.
Use 4 x M2 X 8 Hex bolds with nuts
Have fun and give me I like if you like it. ;-)
To prevent the rubber caps to push in the case use the existing bracket and cut it as in the foto or print the one I designed.
I love tinkering my designs together in Fusion 360. Mostly inspired by things witch have some use. I'm always open for new ideas. If it's within my skills to make it, I'm happy to have a go with it.
Have fun making!