Recommended · for some experience
DIY Lab Bench Power Supply
Why people recommend it
A guide to turning a spare computer power supply into a bench supply, linked both as a suggestion and as the plan people were following.
Watch for: Mains voltage inside, take care
In their words
I got an old PSU which I'd like to make something very useful of it: transforming it in a lab bench power supply like the one in this video.
rtrigo on electronics.stackexchange.com, Sept 2017. CC BY-SA.
I was planning on a temporary solution like this
RSB on electronics.stackexchange.com, Apr 2017. CC BY-SA.