A few weeks ago I tried to make a helix-type lift for a next marble run. The idea is pretty simple and the base material available at a hardware store (okay, things in Germany are metric not inches).
http://imgur.com/iM7AIXE
Not shown are some screws and spacers. Here we have a close up of the ends:
http://imgur.com/O7T9Di9
The biggest issue for me is winding the spiral since I have no workshop, no dedicated machines. So I took household material (a rolling pin) to wrap the aluminium strip around. The outcome assembled together still looks reasonable.
http://imgur.com/xb2BSrT
Unfortunately the precision is less than I hoped. The spiral I expected to get not more out of shape than 2mm. Actually I got 3mm and so the construction will not fit to 16mm marbles. 22mm will work better but are not intended here .
Oh I notice that I am lacking some pictures of the current assembly with the housing. I will post them later. Anyway for the next 16mm-run this lift is deprecated.