Comment by osener
14 hours ago
I can't open those with a coin, the plastic is too soft indeed. But if I stick them to another object using the included sticker I can just rotate the device itself to reach the battery. If you want it to be mobile you can stick it to something small or a 3d printed piece of plastic.
I also do the stick and twist method for opening them, but it always require new adhesive, so not a good solution. I also tried multiple 3d printed jigs for opening but those also didn't work very well
You need the right sized coin. A nickel works best. Anything else doesn't fit right and tears up the plastic or slips out.