Pretty simple enclosure for the LM2596S board that has constant current and constant voltage functionality.

https://www.amazon.com/dp/B0781JC2WK

Use M3x12 socket head cap screw and nut to attach the top to the bottom. Mount the bottom to your desired surface with double-sided tape or the mounting holes in the bottom (or use the M3 hole to go all the way through). Optionally strain relief the wiring using zip ties.

No special printing instructions are required. Don't use supports as the print is designed to print without them.