For the parts "Track.stl" and "Auger.stl" I used the Cura brim setting.

For the part "Star.stl" I used the Cura supports setting.

Parts I Purchased:

1) Gear Motor: DC 6V 60 RPM High Torque Electric Replacement Gear Box Motor (Amazon).

2) Coaxial Power Jack: Coaxial (Radio Shack part number 274-1583).

3) Power Supply: 6VDC (Radio Shack 273-315).

4) 8mm ball bearings (local hardware store, Amazon).

Printing:

Print one each of all parts. When printing "Track.stl" and "Auger.stl" I used the Cura brim setting. When printing "Star.stl" I used the Cura supports setting.

Assembly:

Prior to assembly, test fit and trim, file, sand, etc. all parts as necessary for smooth movement of moving surfaces, and tight fit for non moving surfaces. Depending on the colors you chose and your printer settings, more or less trimming, filing and/or sanding will be required. If the tight fitting components are too loose, add a small dot of cyanoacrylate to each side of the pin, allow to dry completely (I use accelerator to speed the process), then try the fit again. Repeat until tight.

Assemble as per "Assembly.stl". I perform the assembly task in the following order:

1) Carefully remove the brim from the components printed with the brim setting and supports for the component printed with the support setting. Also carefully clean the entry and exit holes in "Track.stl" making sure the 8mm ball bearing easily enters these holes.

2) Slide "Auger.stl" into the larger tube of "Track.stl", making sure it rotates freely. If not, using "Auger.stl", ream the hole until it does. When fully seated in "Track.stl", notice the vertical position of "Auger.stl for the next step.

3) Press the gear motor into position. Make sure the gear motor shaft aligns with the hole in "Auger.stl", then press together such that the motor shaft enters the hole in the bottom of "Auger.stl". The motor shaft must extend into the hole in the bottom of "Auger.stl", and "Auger.stl" must be vertically positioned in "Track.stl" as noted in the previous step.

4) Press "Cap.stl" onto the top of "Track.stl".

5) Press "Star.stl" onto the top of "Auger.stl".

6) Wire the motor such that "Star.stl" rotates clockwise when viewed from the top of the assembly.

7) Test the mechanism by adding the ball bearings to the track and plugging it in. The ball bearings should enter the lower hole and exit the upper hole with ease. If any jamming, hesitancy, etc. is observed, use a modeling knife to slightly enlarge the holes, while being careful not to leave any trimmed plastic strands. Test again and repeat if necessary.

Enjoy!