Cryptocurrency mining is booming again with Ethereum currently being one of the most mined coins. In many countries graphics cards (GPUs) used for the process are hard to find or are much more expensive. For mining purposes, several cards are mounted on a single motherboard with a riser connector and attached to an open external rig for more space to get better cooling air flow.
Most mining rigs are self-built by the operators who always want to get the best price to quality ratio.
Here are a few very practical 3D printable DIY modules you can make yourself and use in your setup.
Here is a somewhat typical mining rig but all the connections of metal profiles and structural elements (red and black plastic) were 3d printed:
Youmagine project page with all the instructions and files:
If you don't want to keep your GPUs on a riser connected to a rigid frame to get more space or flexible arrangements for better cooling, you can use DIY 3d printed card holders.
MMF project page with all the files:
Here is a different type of vertical GPU holder with focused ventilation opening:
Using 3d printing to build your hashing beast is a great way to ensure spare and replacement parts and it gives you much more customization options. You can also get various type of fan holders, air flow focusers, PC component holders, and many other components.