Nimble Rackmount for Gigabyte Brix

**Full build of the Nimble rack w/ BOM will be uploaded later.**

Remixed from Nimble NUC shelf.
4U rackmount for Gigabyte Brix mini PC in a Nimble or six-inch rack

I had to increase the height of the shelf to a 4U to fit the Brix properly, so I figured I would re-design the vent holes at the sides for a more uniform look rather than just adding the extra height with no change. If I iterate on the design, they will likely increase either in number or size. Not sure about the thermal significance of the current ones just yet.

The supports in the center had to be rotated and moved to fit the Brix to VESA mounting holes. They are sized to let the Brix sit on the existing feet while providing extra surface area for it to rest on.