Recommended print settings:

• Material:  PETG
• Layer Height: 0.15 mm or less
• Infill % : 50+
• Supports: Yes
• Print Orientation: Default as modeled

I printed this model from Thingiverse, and am re-uploading to Printables. No changes made to the design, though I did combine the two parts into one STL file, and aligned the lever to the build plate for easier preparation.

From the original description:

Additional parts are

M3 X 16 screw and nut
Spring dismantled from a wooden laundry clip
very little rubber tape to sandwich between the knocker and the chute in case of slippage.