They can be. Because of course there are poorly made commercial units that are only quiet because they have low CADR. But you’ll never be able to get a DIY box as quiet as a well made unit, unless you basically engineer your own air purifier device, use blower motors, etc., but that’s not a Corsi-Rosenthal Box.

It’s not just about aesthetics. That DIY box will be loud as hell.

OP is from the future, when GPUs are a subscription service that processes your graphics online.

Veritasium. Over time I realized his content is mostly about flashy half baked “sciencey” content like Discovery Channel. It’s meant to get an audience and nothing more. It lacks quality control, and fact checking. I only realized how many errors his videos have when he covered a topic I know more about. Also, the whole electricity thing and self driving car debacle only reinforced my views on his content.