RE: Alloy / fibre tube fuse frame?
At one point in time I had a BUNCH of aluminum tubing meant for use in hydraulic lines. It was capable of containing 10,000 PSI. I think the OD was 3/16, maybe 1/8???? The ID would thread to 4-40 perfectly. Sadly it all went to the scrap heap years ago. Maybe a search for a similar product would yield something you can use. It was in 10 foot lengths and you could pick it up from one end and it would support itself.
Good luck!!
Ken