The first one failed. Printed at "Normal" resolution on a Lulzbot mini, It couldn't handle the stresses of the inserted metal parts.
Then I printed it with 0.1mm layer thickness and 1mm walls. Solid and works well.
I did make some adjustments to the design. The original design does not have a relief to keep the bearing's inner race from dragging on the plastic body. I also adjusted the large gear geometry in order to center the hobbing on my hobbed bolt on the feed hole in the main body. I added a small fillet to the wire support tab (the first one stress cracked), and finally I modified the guidler to allow easier insertion of the bearing axle. The last change was really unnecessary because I decided to run it without an axle. The guidler grabs the inner race securely enough that the axle seems redundant. It was either that or grind a flat on each end of the axle to allow the guidler to close enough to grab the filament.
I set mine up with a 16 tooth pulley on the motor. That gives me about a 1:5 ratio, allowing me to use a lower order micro-step setting. The result is less current required for the same torque. The down-side is that there is more stress on the belt due to fewer teeth engaged in the driving pulley.
The weight without the hot end was just over 300 grams.