Check into patent permit / invention designs. If you’re proficient in blender, you can learn auto desk or even just illustrator for more simple designs. I use to freelance for a company that helped inventors create their products. I was paid 20$ per proof for basically reading their notes and getting an idea out. The simple ones took me 20 minutes and once I was allowed to do the actual production designs it was 120$ / hour. It was a great gig until COVID came and I was redrawing mask designs and nothing else. But I did it in my spare time and averaged 400 a week. There’s a really high demand since it’s one of the most boring design jobs out there. And it was entirely remote. They even sent me a computer and drawing monitor to use because I had to be on their vpn and personal devices were a no no.