@Lumpy Those are great. I started to make one myself but ended up needing to upgrade my shopvac and tripped across another option that I’m really pleased with (after 3 months). The Ridgid vacs for homedepot have these contract dust bags: https://www.homedepot.ca/product/multi-fit-dust-bags-for-38-to-53-l-10-14-gal-shop-vac-maximum-mastervac-wet-dry-vacuums-3-pack-/1000141976 (looks like you can get them for other brands too, Homedepot mentioned some other brands on a related link)
I was skeptical, essentially I took a new large (I think it was 16 gallon) vac, assembled it, build a silencer cabinet for it, and put one of these in. Then I largely forgot about it until my vac would start and immediately shut off last week. I opened the cabinet, took the lid off the vac and it was pristine & clean inside. I carefully unhooked the rubber opening on the intake, spilled a tiny bit of dust (will be more careful next time), tossed it in a trash bag for disposal and installed a new filter bag. Virtually no dust made it through to the drum of the vaccum and it was super easy to clean up. The downsides are the capacity is lowered a bit by the bag and you have the on-going cost of bags but other than that, it’s a potential option for those it appeals to.