Basics

A Rasberry Pi , Open Rack format, Modular, Compute Cluster
Used for Render Farms , reducing Ai Training Time , NAS processing, and Servers
Is even more modular, upgrade-able than standard rack mount systems as it is made of many small RPi's
May be less fast/optimized, so eventually a proper motherboard based system will be more (cost) effective
Also allows for easy maitnence due to modules being swappable + easier to fix than larger boards
Will use ethernet for networking

To-Do

Choose a software/firmware
See what power is best (ie no throttling/bottlenecks) options are: USB (easiest), Barrel Jack (more annoying to implement, especially OTS, but do-able, and POE more costly,, requires adapters
Calculate best number of boards per OpenRack
- Going to guess 20 for now to leave room for electronics + networking
Look into other networking methos (modified toslink, infiniband, higher gb/s ethernet etc)
Make graphs for cost/core and performance/size etc

Concept is a (Raspberry) pie sitting on a slid out rack mount tray, on a server cabinet (made to look somewhat like an oven, yet still recognisable as a server cabinet), letting out steam as it cools.
Low quality concept sketch here: