Simple one-piece: https://www.printables.com/model/33600-credit-card-wallet
Storage for SIM/MicroSD cards: https://www.printables.com/model/246538-minimalistic-card-wallet
Enclosed two-piece: https://www.printables.com/model/244836-parametric-snap-together-credit-card-wallet-v3
Key hub: https://www.printables.com/model/1486968-card-wallet-with-money-clip-and-key-hub
Concealed keys: https://www.thingiverse.com/thing:3230667
Hinged: https://www.thingiverse.com/thing:2819571
Spare key tray only: https://www.thingiverse.com/thing:2992263
This is a small / compact USB charger for RYOBI 18V One+ batteries.It uses the Ryobi 30001044 replacement terminal that snaps in. You can purchase different 12-24V Sockets to install. I have used one that has two QC 3.0 USB ports.I had nice short Amazon links here of the parts I used, but Thingiverse edited my summary and changed all the links so they could make money off of them. Check out the models on https://www.prusaprinters.org/prints/39392-ryobi-18v-battery-mini-usb-charger
This one uses keystone 209 contacts:
https://www.printables.com/model/905677-ryobi-18v-dual-qc30-usb-charger
Another variation, but more electronics work:
https://www.thingiverse.com/thing:4220395