This design for an external adapter lets you use a computer power supply without modifying it.
Convert ATX To DC Power Supply, PDF, Direct Current
Convert ATX Power Supply to Bench Supply
Convert a PC PS to a Bench Power Supply - element14 Community
Converting Computer ATX Power Supply to Lab Bench Power Supply
Convert ATX To DC Power Supply, PDF, Direct Current
DIY Bench Power Supply From ATX PSU - Instructables
Easily Convert an ATX Power Supply to a Lab Power Supply
ATX Bench Power Supply by robertguy - Thingiverse
Turn A Computer Power Supply Into Bench Power - Make - PDF, PDF, Power Supply
Encyclopedia of ATX to Bench Power Supply Conversion - Instructables
I Made My Own Bench Power Supply Using Old Computer PSU and 3D printing. Make one by your self the stl files and circuit connection are available on Instructables. : r/diyelectronics