This is a simple rig to implement a precisely focused air jet at the tip of the hot end by using an external blower. It works very well, but it is very noisy and only a little better than the much simpler modification of the duct on the standard ANYCUBIC blower: ANYCUBIC Kossel Delta Filament Cooler (Fan Duct). The external blower air jet mount is shown on the left in the cover photo, the improved duct for the standard blower is on the right. The main difference is that this external blower rig can allow you to print some very clean, very thin, structures at or near full speed -- however, after extensive testing, we don't feel that this is worth the trouble for most printing tasks.

The external blower used is an Intex Quick Fill 100, which is an AC-powered unit intended to inflate mattresses, etc. When running, it sounds like a vacuum cleaner and slowly gets a bit warm, so I recommend turning it on only for the most critical parts of a print. The funnel bayonets onto the blower and the 1/4" clear plastic tubing runs to the printed mount, which holds onto a metal strip on the printer's head assembly (the one intended to mount the auto-leveling probe) thanks to a 1/4" x 7/8" ceramic block magnet. The blower, tubing, and magnets are easily sourced (e.g., on the shelves of a typical WalMart). Although tight fits mean that glue shouldn't be needed, I did use a bit of cyanoacrylate to help hold the magnet in the 3D-printed mount.