Update 12/14: I have added larger opening slip on ducts now. Details in Instructions. This is a dual 30mm x 10mm fan system for use on a Solidoodle printer with Lawsy's carriage. You can find his files here : http://www.thingiverse.com/thing:104059 I printed these with support on in slic3r at 0.1mm. Constructive criticisms, comments, and questions are welcome. The arms mount up using the M3 bolts for the carriage's front bearing bracket. The fans are screwed on with what came with your fan, those screws work great, if not you can use M3 bolts. I only used two for each, one to mount the fan on the arm, and one in the opposite corner to keep the duct snug. The duct itself slips over the head of the bolt, then is secured in the opposite corner with a screw. Update 12/14: The slipon thicker ducts have a much larger opening and are printable without support. I saw a decent improvement in PLA overhangs from the original to these ducts. Fitment will depend on your calibration, I oversized them 0.1mm to just hug the fan. Mine printed at 30.18mm, after shaving off the squished first layer. If extra friction is needed, or to tighten them up a bit, use electrical tape. Happy Printing!