12VDC to USB converter dongle, many applications where 12V power is available and a USB interface is needed for powering electronic devices. (such as on many 3D printer with a 12V power supply).
Uses USB DC 7V-24V to 5V 3A Step Down KIS3R33S Module For Arduino LM2596, readily available for <$3 with shipping! Purchase links can be found on project page here: http://bigcooter.com/archives/1587
M3 screws are used for holding the housing halves together.
This thing was made with Tinkercad. Edit it online https://www.tinkercad.com/things/iVr4HcHTZNe
The part shown here was printed in PLA, which is well suited for tapping M3 threads into, or self tapping of M3 screws.