Although there is nothing toxic about 3D printing with ABS (check out an MSDS for ABS and research posts such as http://www.instructables.com/id/Is-3D-Printing-Safe-or-DIY-Testing-for-HCN-from-/ ), it does have some odor.  The magnitude can be reduced by enclosing the printer (presumably giving the volatiles time to condense as they cool), but it would be nice to exhaust the printer, venting outside or into an activated carbon filter if indoors.  I’ve done both and I plan to further improve the latter method for our new Solidoodle 3.  For the Solidoodle 2, I (1) cut plexiglass to the sizes of the sides and top, added adhesive-backed magnetic tape, and applied the sheets to all sides; (2) reduced other gaps around the frame; and (3) attached a 4″ ducting blower fan to a 4″ clothes dryer ducted hose; and attached the hose to a hole I made into one of the plexiglass sheets; and (4) set up a 4″ PVC elbow with some cut sheets from an activated carbon filter sheet.  By reducing the leakage into the printer from the room, I can use this lightweight blower fan to move a large part of the ABS fumes-enriched air into the filters.  With the Solidoodle 3, I plan to do the same thing but make a small hole in the back of the printer where the spool mount currently attaches.  There will be many more details and pics in a future post, but here is a SketchUp sketch of what I’m describing.

exhaust design showing back of Solidoodle 3 printer with custom-designed and printed PVC fittings and tube to connect to a 4-inch exhaust hose yet retaining the functionality of a spool mount for the ABS plastic.