An exemplary display of the latter is The Citadel. Over the course of three years, redditor [Shadowman39] pieced together this monstrous K’nex structure. With over 17 different paths(!), ...

He used a K’nex 12V motor because it plugs in rather than requiring batteries. After the coil had been completely wound he set it to rotate the assembly over a period of several days while the ...