Well my first ones were 1.6mm, but they are WAYYY too hard to get in/out of the socket. I basically had to wriggle it back and forth multiple times for it to fit in the socket and getting it out felt like I was going to rip the whole board with it. I measured the original ram I have here and it's around 1.2mm, but if it needs to be a little bigger, then I'll do some tricks I guess heh.
I made a two layer version out of the schematics that fly around on the interwebs because cheap:
Couldn't get them to work reliably yet because of the whole PCB thickness thing.
If you wiggle them around before use and put on rubber bands they are ok for a while.
What thickness did you choose for yours? I ordered some in 1.6mm as well as 1.2mm from JLCPCB.
1.6mm is really tough to get into the socket and 1.2mm is more on the floppy side of things.