Protective Case for RUI DENG RUIDENG RD TECH UM25C USB-Tester to cover the open boards and protect/support the USB-Ports & the switch. 

Created this thing back in 2019 completely from scratch in SketchUp - all measurements are made on my own RUIDENG UM25C on which it still works flawlessly.

MAY fit on other RUIDENG models unless some ports are not needed or different (micro-USB/USB-C) Don't know if non-Bluetooth® models will also fit in terms of overall height, but it seems so at the UM25 without "C". Only the Bluetooth® slide-switch (and the board of couse) is missing. The newest model UM34C could fit also, despite this model is lacking the USB-C Out and on the non-Bluetooth® model the switch too.

The UM24(C) model seems to be incompatible except for the overall case design. Ports & Buttons are completely different.

Supports are possibly needed for the USB-Port and Switch - infill can be as you like it. I've used 50% infill - up to 100% are fine too and make no big difference in time and material use.

Post-Printing

• After sucessful printing remove the supports (if printed) and check all edges for overhangs, bubbles and sand them down or remove them with a exacto knife.
• Testfit the lid on the base - it has to sit flush without gaps between lid & base case.
• Unscrew your RUIDENG device and keep the screws separated (short for lid & long for base case)
• Put in the acrylic bottom plate at first, followed by the Bluetooth® board. Eventually you have to sand down the unprecise machined edges of the circuit board (left & right at the USB Connectors) to fit in the case.
• Next add the main board with display and ensure the four buttons to not catch on the edges and sit correct behind the push buttons of the case.
• Cover it with the acrylic window plate and finish the sandwich by putting the lid on and ensure it sits correct.
• Put the screws back in place (short for lid & long for base case) and you´re done!

Note

The alternative magnet body has 6 internal cutouts for 10x2mm round magnets, so you can attach the thing securely to any magnetic surface.