many times i have seen studies that shows concern values of solid particles in the air when you use a 3D printer. And it says that if you use a toxic plastic, like ABS, is as harmful like smoking. this design find decrease these values. I have designed this thing for a prusa 3 box, but it can be used for a single frame, with the only inconvenience that it can be seen since the front side. I have used a Nidec VA450DC fan, but you can use the fan that you want if it have the same dimensions. 105 mm between bolts and 120 mm of wide. The bolts are a M4 x 50 (the Nidec thickness are 38 mm). the top of the thing is for connect a alluminium flexible tube, to get out the gasses.