I haven't seen the dune cylinder case actually be available though... Really wanted the cryoig Ola..
Looking at the cylinder images I don't like it, it seems to waste a lot of space for no great benefit. Seems to me you could get some cylinder then 3D print a cage/chassis that slotted into it. That would be relatively easy. Then the backplate needs to be cut out, which would probably mean outsourcing to get a really clean cut. You can get off-cuts of 'plastic' pipe in large diameter (sewerage pipes and so on) that would make for easy work, but also things like stainless. So for me such a case would be quite price sensitive- like £100 not £200.
I have so many half finished projects that you should take anything I say with a pinch of salt but one I've started is a 86-64 (the horrible and pointless Cherry Trail Atomic Pi) SBC in a motorcycle silencer*- a 'straight through' slash-cut chrome job (£50 but can be had cheaper, say £30). For non-bikers these are the sort of things you see on Harley customs. You need straight through as you don't want baffles inside the tube, you want it empty.
Sorry, off topic.
*muffler in the USA I think, in other words not the whole exhaust system, just the bit on the end.