There are a million variations on projects where you turn a PC (or other) power supply into a bench top power supply. I don’t know what my attraction is to this category of project (I have never bothered to build one), but they always catch my eye and I always at least imagine myself one day building one.
Here’s a project on Instructables for building a supply using parts all bought via AliExpress, the most expensive being a US$27 supply controller and an $8 36V 1.4A 50W power supply used for powering LED strip lights.
With the parts in hand, it’s simply a matter of wiring everything together and housing it in a 3D printed enclosure. The .STL files for that are included.