6" to 4" adapter for laser/grow tent ventilation fan

thingiverse

I wanted the 400 CFM version of the ventilation fans popular for lasers/grow tents, but wanted to use a 4" duct. I realize this will cost some CFMs, but hopefully not down to 200 CFM which was all I found for the 4" versions. Here is the fan I used: https://www.amazon.com/gp/product/B009LCEUEK/ref=oh_aui_detailpage_o05_s00?ie=UTF8&psc=1 Took a few tries to get it right, but the 6" inside diameter end has a slight taper and will friction fit over the fan in/out port. The 4" end is an outside diameter and the 4" duct slips over it. Because there was so little surface touching the printer bed I had to use a raft to avoid warping even with PLA.