This is a 3d-printed pogo-pin programming jig for Tomu (https://tomu.im/), a tiny USB device. Normally you can use the built-in USB bootloader to reprogram it,
...Plus but in the cases where you can't, having a jig to align the SWD programming pins on the bottom can help.
To build this jig you will need:
* the 3d printed parts here
* 4 pogo pins, like these [P111-E 1.3mm Diameter, 33.30mm long test pins](https://www.amazon.com/exec/obidos/ASIN/B007Q8JRZ8/ref=nosim&tag=todbotblog-20)
* two [Adafruit Perma-Proto Quarter boards](https://www.amazon.com/exec/obidos/ASIN/B00SK8OO6U/ref=nosim&tag=todbotblog-20)
* some 4-40 0.75" or [M3 20cm stand-offs](https://www.amazon.com/exec/obidos/ASIN/B06Y5TJXY1/ref=nosim&tag=todbotblog-20)
* a compatible JTAG/SWD, like this [$8 STLink v2](https://www.amazon.com/exec/obidos/ASIN/B01J7N3RE6/ref=nosim&tag=todbotblog-20) one
Also handy is a small USB hub with per-port power switches, like this [4-port Sabrent USB hub](https://www.amazon.com/exec/obidos/ASIN/B00JX1ZS5O/ref=nosim&tag=todbotblog-20)
When soldering the pogo pins, make sure they poke out about 1.5mm from the 3d-printed base.
