So I found these Key Stone sleds, I had in my parts collection & they are tinny! I had to use a single strand copper wire to save space! I'v used this kind of wire before & it's good for battery connections

I had some magnets here from an other project, I drilled 7/64" holes in the case & the back to accommodate them. I used Crazy Glue to secure them, I also cut the screw heads off the original screws to cover the hole, also crazy glued in

I cut a grove in the sled on the + wire side to reese the + wire were it cross's over to the space in board were it fits fine

The - wire has plenty of room

I also had to file the conners of the sled on the - end.
So now I have an ERM 75c with the original case & an 18650 sled, for swap & go battery changes

BTW that the battery that came with, I unsoldered the wires & rewrapped it