I used some old PLA I had lying around, but this should probably be done in something higher temperature (PETG or ABS), because if the nozzle gets too close to your hotend, you'll experience some drooping.

Update: I'm a year into using this setup, and i adore it. It's simple, and it works so well, i haven't even bothered to reprint it in a better filament. Parts cooling is good, and i have only one minor complaint: Periodically, you may wish to ensure the cooling fan is firmly in place on the cooling duct. It likes to vibrate out a little.

And yes, I need to shorten those wires. It's on the list.