I designed these murble run with two electric options (drive with a normal AAA-batterie or with a solar modul) and also for hand drive. You can use murbles with a diameter of 12 mm. For assembly, first press bearing 1 into the cover. Then the shaft is pushed through and the helix is placed on the shaft. Then the bearing 2 is mounted and depending on the variant, the gear or the manual drive is attached. The electric motor will mounted with two screws. At the end you press the two pins in the cover and assembly it with the marble run.