Marble elevator

Half a meter vertical transport.
Intrigued by the marble run transport snail 152 mm 7 twists from thomasdr http://www.thingiverse.com/thing:613224
I decided to surprise my grandchildren with an impressive marble elevator and printed three transport snails combined on a threaded M4 rod. The housing has a marble IN and a marble OUT piece, connected with three extensions using connecting elements. Standard glass 16 mm marbles fit well, but also smaller ones are lifted without problems.
All parts print easy without supports but high infill to make them strong. If 14 cm height is too much for your printer, just make the extensions shorter and use one more connecting element. For some printers it might be a good idea to have a 10mm brim at the base of the extensions and screw.
The M4 threaded rod has a 2mm diameter hole at the bottom in order to fix it to the motor connector by a 2mm bolt. Just to make sure it stays in place when it is loaded.
The motor is a geared DC motor. Because no