Marks Rpi Cluster continues to run 24/7 in a slightly reduced capacity. That is the Pi4's are going 24/7 but the Pi3's are on during the weekend. The cluster is still running Einstein BRP4 work exclusively.
Blade Rack for Pi4
There is an updated version of the Blade Rack for Pi4's which I have ordered from BitScope. It follows a similar design to the one used for the Pi3's but each Pi gets a 30mm fan for cooling. Due to the extra fans I expect it will be a lot noisier that my existing Blade Rack, even though I ordered the desktop version of it.
I have 12 x Pi4 8GB, but 3 are still in boxes so this will allow me to move all of them into the one enclosure and get them all running 24/7. I need to repurpose the power supply from my existing Blade Rack so it will go off-line.
BitScope make larger versions of their Rack/Desktop that hold more Pi's but its rather difficult getting a hold of a Pi4 8GB at the moment.