My daughter and I built this Marbleocity Archimedes Screw Marble Machine kit over the Christmas break this year. Building it was pretty straightforward and took about 1 hour, but some of that time was actually just waiting between steps to let the glue dry. The motorization kit, which is sold separately, is highly recommended and makes it a lot more fun!
There is some educational value in that the kit contains some comic strip explanations of how the archimedes screw works and how the motor works as well, but the primary value of this is the mesmerizing effect of watching the marbles go up the screw, down the funnel, and then down through the maze over and over and over….