The BoM is missing 10 2x3mm magnets, some wire, connectors, and that you have to drill three holes.  I drilled a 3/32" (2.5mm) hole in the base to thread the motor wires up through the center of the tree to a 3/32" hole off center at the top for the wires to exit, being careful not to interfere with the top of the "tree".  Also make sure you don't block the raceway with the wires.  You need to drill a 5/64" (2mm) hole to shoot a screw through the center top to the hole on the top of the "tree trunk".  Then you need to secure the bottom of the raceway in such a way that the marbles will roll and not hit a flat spot.

Thanks, Sean!  I appreciate it.

Hello, thank for this project. But where are the stl files?

Hey, they are available to download on the MakerWorld link, but if you don't want to download them from there, I can make a github, and/or thingiverse soon. 

Hello Sean, thank you for your answer and sorry I didn't see the link first 🙂

No problem to download from MakerWorld, I have a BambyLab P1S.

Thanks for the project idea!  May you post the STL files for downloading?  Also, would this motor be compatible:

https://www.sumozade.com/product/micro-metal-gearmotor-hp-6v-1500rpm?gQT=1

Thanks!
Tom  Hammond

That looks like it might be too low of a ratio(too fast), but yeah that style motor should fit. The one I used was around 298:1 gear ratio. 

Hey Sean, thanks for the reply.  Would this motor be closer to what you recommend?  I think that it has the 298:1 ratio like you said, but not sure.

https://www.aliexpress.us/item/3256806769029682.html

Thank you!

Tom