Parts. I acquired the following parts: • One N20 6VDC 30RPM gear motor. • One twin AAA cell battery pack with wires and switch. • Two AAA batteries. • Five 11mm diameter ball bearings. I 3D printed the following parts using Ultimaker Cura 4.12.1 Engineering Profile at .1mm layer height, 15% infill: • One "Base.stl". • One "Wheel 6.stl". Depending on your slicer, printer, printer settings and the colors you chose, trimming, filing, drilling and/or sanding may be required. I carefully filed all edges that contacted the build plate to make absolutely certain that all build plate "ooze" is removed and that all edges are smooth using small jewelers files and plenty of patience. Assembly. To assemble the model, I performed the following steps: • Slid the battery pack wires through the hole in the rear of "Base.stl" and through the base motor mount cavity, then soldered the wires to the gear motor such that the gear motor shaft rotated clockwise when viewed from the motor shaft end of the gear motor with power applied. • Pressed the gear motor into the motor mount cavity. • Pressed "Wheel 6.stl" onto the gear motor shaft. • Aligned the wheel with the track. With assembly complete, I turned off the battery pack switch, installed the batteries, turned on the battery pack switch, positioned the ball bearings on the track, and off it went! And that is how I 3D printed and assembled "Marblevator, Simple". See, I told you it was simple and I hope you enjoyed it!