This is a case for a 100W boost power supply that can be purchased on eBay. Unfortunately the supply doesn't have a part number, but it's listed as "DC-DC 100W 3-35V 12V to 3.5-35V Boost Step-up Module Power Supply LED Voltmeter". I purchased from a seller named zjpower18.
Case includes a bit of extra room around the PCB, standoff pads, and posts that can be re-melted to mount supply permanently in the case. The lid includes a viewing hole for the display and a button that switches the display between input and output voltage.
The button can be tricky to print well and might require some manual trimming after printing to get it to fit and work well.
Requires four small screws to mount lid to case.
4/24/2019: Added a version that has external screw mount tabs. I placed the tabs near the wire access since that will keep the case as narrow as possible and wires must enter/exit in that area anyway.
Designed in Autodesk Inventor 2014.