I really liked reading about the history of your homelab.
How do you like the 3d printed rack enclosure? Is it strong enough to hold the weight and heat from the server?
I used PETG to print it, which should support the heat without problems. I also added two fans behind, so that the disks and enclosure stays cold. For now, I only have 4 drives in it, and it does not move at all and holds perfectly fine.
These days data center capacity is measured with wattage. What's yours? My homelab is about 650Ws as is, and should cost around 300$/mo in electricity (california premium).
Fortunately, the R740 is around 230W, and the switches, routers, and everything around seems to only take 40W. Which means I'm below 300W, and I guess we have cheaper electricity in France as I don't pay as much as you (I think less than 50€/month for the homelab)