This set of parts adds a fume hood to your Cupcake CNC that's meant to be used along with the Cupcake "oven" covers:
There are holes for the filament feed, Z-rod access (for both left and right handed user), and a 3" port that you can hook up to the air handling solution of your choice (maybe this? http://www.thingiverse.com/thing:7152). It sets on the top bolts of the Cupcake for easy installation an removal.
More pics here:
Basically just cut the PETG parts, snap them together, and seal the thing up with clear packing tape to make the main body. Ideally you'd use this with the MakerBot spindle or a similar spindle setup with a 1/4" HDPE filament feed tube. The two small circular parts are washers for the push connect hardware for the filament tube that's installed in the center of the housing. You'll need to extend one of the Z rods through the top of the enclosure or use a Z-min endstop to zero the Z-axis with the hood in place:
The 3" port on the back is simply a 3" drain port from Home Depot.
I experimented with using laser cut sticky backed EVA foam (craft foam) for the gaskets on this project and it worked out reasonably well. Just cut and stick where the outlines for the gaskets are. There's a gasket for the port on the back and the two Z-rod access holes (use the one with the hole for the Z-rod extension and the solid one to seal off the other).