It’s really weird construction, the inner structure is steel but is mounted with all these stiff rubber grommets to the fairly thick outside aluminum structure.
The way I justified it to myself is to replace my rapidly aging hp proliant g7 n54l microserver; it is incredibly hard to find little cases with 5.25" bays.
I’ve got a Silverstone CS01-HS I bought and never used because it isn’t nearly as practical as I thought it would be once I had my hands on it.
Have that, is nice for sure.
Kind of odd there’s no mini-ITX cases that copies the idea of the HP microserver. Those that exists have all dropped the 5.25, even if there’s room for one! 
If you survive with only two of them, SilverStone SG02-F. I was toying with the idea a while ago to build an automatic blueray ripper in a case like that. Two blueray players that rips and disks you put in it. Then friends and family could borrow it when they needed to rip something.
Even better, the iStarUSA Case S-35EX. Might be a bit hard to get hold of though. It’s no looker, but it’s basically just a delivery system for three 5.25 drives in a mini tower.
This is really cool. The hard drive mount is pretty well thought through. Only downside is that my printer only can print 15x15x15cm.
Most Silverstone cases. I enjoyed building in the RVZ01-E to specifically repurpose older parts, but I’m more interested in the RM600 chassis that they showcased over a year ago now. It was rack mountable with minimal HDD bays. I want to vert so badly.