Inspired by MBCook's plywood air filter. I didn't have carpentry tools or scrap plywood ready to hand, but I did have some nice flat cardboard boxes and an urgent desire to do something about my Thing-O-Matic's ABS fumes.

As he surmised, it is possible to make it much lower for printers with the Mk 7 stepstruder. I wanted to be able to store my Thing-O-Matic in a cabinet with a height constraint, so I made the lower 'fume hood' only an inch tall. (This required a cutout for the Z motor, which I then covered with a cute little cupola...which is probably overkill but might as well commit to the bit, right?

I used a cabin filter that would fit in my car, with dimensions just shy of 9x11x1.75". Like MBCook suggested, I built the filter box to be able to open on the side. I put the fans forward, to be almost directly over the heater, and also to allow the filter lifespan to be doubled by reversing the filter to bring fresh material into the airflow path. This is almost certainly either overkill or wishful thinking, but if I'm going to go to this trouble, I'd like to get the most out of it that I can.

I punched a hole in the filter and inserted a little cardboard straw (from an Aerotech model rocket motor package, used to store the igniter) to feed the filament through. The thought was that, if I had just made a hole in the filter, there could theoretically be a path for air to get pulled by the fans that bypassed the filter. The straw is supposed to fix that, by forcing any air pulled by the fans to go only through the filter...this is probably also either overkill or wishful thinking, but what can ya do? I might put a little sponge in there at some point, for cleaning the filament as it comes in.

The PDF is dimensionally correct to my intentions, but given the non-zero thickness of the cardboard...it's really more what you'd call an aspiration or guideline than a hard-and-fast blueprint. Tape will be your friend.

Preliminary test results suggest that there's still plenty of space around the openings for outgassing to escape...my printer is currently down for maintenance (aren't they always?) but eventually I'll see if paneling over the sides and back with countspatula's Side Panel Clips helps!

(Ignore the STL file, Thingiverse insisted on having something not in PDF format and it wouldn't take my SVG files, for whatever reason.)