This cleaner is quite simple to make. Especially if one gets lucky and finds a squirrel cage blower from a hot air furnace like I did.  It has a 3 speeds and uses 20X20X1 inch filters, but I found out my original plan to use two MicroAllergen  1000 rated filters on each caused the fan to work at high speed all the time.  Then I tried one MicroAllergen  1000 filters on each side plus a cheaper one on each side. Same thing.  I found out that just one filter per side allowed me to take advantage of the  multi-speed aspect.  I have it mounted on a cart with wheels so it is easily moved round the studio.  I have seen these hanging from the ceiling.  In the second picture you can see that the top is hinged to easily remove filters.
     When grinding blades I roll it up  to the side and it works really well.  I have have seen simular fans for $100 plus. This was build from scrap wood, fan free, filters $9.00 each.