Creator here!

I did consider Euro Rack, 19" racks, MiniATX and other case standards. But with any of these options, i wouldnt be able to keep the price low. The case including all parts and assembly cost is roughly at 20€ per device. It's an off-the-shelf part, with only lasercutted parts in two materials, and a single custom component which is yet to be determined what's the cheapest manufacturing option.

I wanted to keep the price low and any of the options above would increase the price by at least 40€, which is a subatantial part of the components