Depending on the job, you can also do it better yourself than what you can reasonably pay for.

I built a custom shelf for my closet. It'd have costed me an arm and a leg to have someone else do that, even with a tech worker's salary.

I also built a custom walk-in closet. It took me a day, saved me over 2k and I got a better quality closet out of it. (You find find built yourself a walk-in-closet kits that are easy to assemble, it really isn't that hard, just don't get the home depot level quality ones.)

Depends if you would be getting paid during the time spent doing these projects. People with flexible vacation time might even be getting paid while doing the work. But otherwise weekends and evenings are great times for smaller home projects.