SIM-sized payment card holder for 22mm watch straps/bands

This lets you mount a SIM sized (well, ID000-sized) payment card onto your 22mm watchstrap, letting you pay with any watch. I use it on my Pebble Time to pay and it works quite well.

Another group that's interested in SIM-sized payment cards is RFID implant people (as those are easier to convert to implants due to expected antenna resistance or smth), so they tend to keep a list of some known providers of them here.

I use it with Vimpaygo (which I believe is Germany-only, and is prepaid), but LAKS mini card (europe-wide) and Helgeland Sparebank (norway) also exist. There may also be other options out there.

If you want to mod a full sized card, this is probably not the one for you, unless you remix this and just grab the back holdy bits or something.

Print with supports, with the card hole facing up.

Here's some things to keep in mind:

• Unlike paying with your phone, you'll sometimes need to enter your PIN with these (just like paying contactlessly with your card. Limits for what triggers a PIN are set by each bank/country).
  • As a note: Vimpay randomly assigns the PIN and does not let you change it.
  • With Vimpay, if you want to avoid entering your PIN, you can go in the app and press a few buttons to reset the PIN requirement counter after you've done a few transactions (up to 6x <50eur), I've never actually had to enter my PIN because of this.
• I had the original model fall off when tugged (got stuck on my shopping bag), so I expanded the back holdy bits quite a bit. I've had it in my wrist for 1.5 years now and haven't had it fall. It's also reasonably waterproof.
• The fit with at least the Vimpaygo, this filament (random black PLA), and this printer (mk4 or maybe mk3.5, can't remember which I used) is quite tight, and I didn't have my card fall off even after 1.5 years of use with it facing down. If your fit isn't so tight, then I recommend re-printing it with the Y axis scaled down slightly so that it grips tighter. Applying some force to insert the card is the intended way of installing the card.
  • On that note: To extract the card from the last print, I had to carefully cut the print open with a plier. So don't put your card in fully unless you're ready to commit to the exact model you printed.
• Visually it does not stick out very much with my watchstrap, but it's black/gray watch, black watchstrap, black filament. No one ever noticed it or asked questions about it, not even in hacker events :) You can do your design as overt or covert as you like. I included pictures of how it looks like on my wrist.
• For me the fit is great with this velcro watchstrap but I haven't tried it on others, maybe you need to make the back arms a bit less wide for it to be able to be installed on some types of watchstraps. It won't work on metal at all though.