Printrbot Metal fan duct to keep tall parts straight by cooling symmetrically.
Scale up to 25.4 scale as it was designed in inches. Rotate so is prints up from the square flange. Baseplate-only support if your printer is zoned in. Pictured in ABS (higher melting point) with the installed duct printing the next duct copy. The small dime on the inside of the flange can be popped off to increase flow. It is there for ease of printing. Tall towers tend to lean into the airflow so when I expanded to 10 inches tall the flow from only one side caused tall thin parts to lean. Breaking the flow into three flows avoids the lean. There are many obstacles in the Printrbot Metal that are reflected in this file. If you don't have that printer you could leave off the localized thinned portions of the ducts. Hand tap with a 4-40 (English) tap and that makes a good vibration tolerant thread fit on the metric screws that came with the Printrbot Metal. That avoids needing backup nuts on the four flange screws. Do not over tighten as it not only will strip the plastic threads but it will drag down the fan motor if the fan is bowed in the tightening process. Just tighten till the screw heads touch down and no further. The tight threads will keep the screws from backing out for a long time.