I've done it.
Way back when i had a Black and Decker canister, which had a "reversed" wand like old hoovers or filterqueens. I made an upholstery tool out of soda cans i used one to make a neck and attached it to a partially flattened base with a hole cut in it, i only tried it out once or twice before i threw it away.
And about ...6 years ago i made a separator for a shop vac i had purchased. the plan was to use it like a central vacuum. I took a 5 gallon bucket and i think a 6 qt funnel. Initially i set it up like a normal cyclone (narrow end at the bottom) but found that lighter weight debris would just spin around the top of it, never depositing into the bucket. So i inverted the funnel and aimed the inlet slightly downwards, connected the vac to the separator with 2" pvc pipe to try to have as smooth an air path as possible. It seemed to work much better in this configuration.
I also made a hose for that "central vac" 2 8' shop vac hoses together using a dirt devil handvac hose end, i used rubber bands to attach a kirby classic cord plugged into a pigtail to power the lux PN-5 nozzle i was using with it.
