Hi @bryan, the HL15 chassis would be 16G cold roll steel and we will be selling additional backplanes in the store in the future. I’m not sure about the drive cages but if there is a need for them or if you want to make a special order in the future it may be something we can do.
the main issue I see is that the HL15 would not have the additional standoffs for the backplanes to mount to for the additional rows. but if you wanted to fabricate and edit the chassis then you will need to make new standoffs to make this work.