For the Central Coast Model Railroad (part of the San Luis Obispo Railroad Museum) I got a nice Dewalt vacuum.? No, it is not miniature, but kits of smaller accessories are available.
First, none of this seems to be what you are looking for.? I just provide it as some background.
We found the regular cheap Craftsman shop vacs put a LOT of dust back into the air.? If somebody did some vacuuming in one area of the room, trains would not run in that area until the virtually invisible fine dust was cleaned off the rail heads.
It is the DeWalt DCV581H.? It is both corded and cordless and it is VERY handy to just grab it and use it on battery for a quick clean up job.? It is very well sealed and does not spew dust.? This is the vacuum.? You buy the battery and charger separately.
We also bought some brand of automotive detailing attachments that were of small size.? I don't remember what.? DeWalt has one.? I could not find it on Amazon, but maybe it is there.? Here it is at Home Depot.
There are many such kits under "Car Cleaning" or "Automotive" or "Micro" or "keyboard crevice cleaning" attachments.
Of course, this is still a big bulky vacuum, but it will do everything.? You might look at smaller DeWalt offerings that have good filtering in them.
For your need, this is not miniature as what you are looking for, but miniature usually doesn't work very well in my opinion.
If I were looking for something smaller, I might consider this smaller Dewalt.? I have no personal experience, but the reviews suggest it is in a difference class than the $30 vacuums that just don't work very well.
Come to think of it, I may have to get one, try it out, and donate it to the museum railroad as an alternative to the larger DeWalt 581.? Or maybe keep it to replace my nearly useless "Dustbuster.'
It does seem that really good vacuums do cost a bit.? But a lousy vacuum is not very satisfying.
Charles E. "Chuck" Kinzer