I'm not clear, is the system enclosure plastic? Not trying to detract from this good-looking project, but that's not a great material for conducting out heat.

I did a 3D printed 10-HDD drive bay a while back using a glass-infused resin (higher HDT so it doesn't soften as easily over time and weight). Works great, but was wishing I had similar ease and accessibility of aluminum sheet metal manufacturing:

https://grabcad.com/library/10-bay-hard-disk-drive-cage-for-...

OP claims that the power draw is only 20 watts and that they're planning to replace the 3D printed panels for laser cut metal ones anyway

This is nice! But what is the point of the battery?