Might sound like a basic question but how are you guys building your rigs with that many GPUs?

What I've done so far is I built my racks using cheap framing lumber... I just make sure MOBO has some spacing with wood using plastic pieces.

No way I'll invest in an aluminium frame at $100... I prefer to keep that money for GPUs.

Here are those masterpieces (there are actually two racks there... I just built them so they could be stacked):

https://i.imgur.com/xxiqNP4.jpg

I've seen those shelves being used a lot: https://www.amazon.com/Seville-Classics-UltraZinc-Shelving-Wheels/dp/B07CJVL5BK

... could have 6 rigs on one shelf. I'm wondering how I could "hang" GPUs on them though. What kind of frame/rack do you suggest?