I loved my old aiwa Minidisc Player and I wanted to keep it functional. The original LIB-902 LiIon battery had leaked and was dead anyway. So I discovered that already some adapter from the 10440 cells are available. But I wanted them to be a little bit more sophisticated.
So I designed my own one. I hat a box of springs laying around and used them to contact the cell inside the adapter and also to keep it in place. For the negative pole I used a M5 countersunk screw. Screwed it one time in to cut the thread. Then I soldered the top to make it flat and screwed it back in with a plier and sanded it a little bit down. The spring can be screwed on the thread of the M5 screw from the other side. Makes nice electrical contact this way and the spring doesn't come loose when the 10440 cell is removed for external charge for example.
Maybe someone likes the idea and has also use of it.
Das Filament PLA