I've seen the tracks from "Transmit1", printed and tested them.
Then there were some thoughts in my mind, which curves, with which radius and angle,
will be possible and useful, and can I increase the grade (angle of slope) .
After a while I find a schematic which curves are possible, but not a lot of them are useful.
Nontheless, I designed, in my available CAD, a custumized curve, to switch
between curve size, angle and grade.
The four curves I loaded up, are the useful ones for me.
(There is a picture that shows the possible curves to choose)
The end of the curves are designed a little bit stiff, so they fit a little bit strong into the plates.
But so the Curve 1x120, 1x240 and 6x60 can be used without support.
The Curve 2x180 need some support, like shown in the picture, or it will tip over.
They all have a "angle of slope" about 35 degree, so the marble can went troug with some speed.
See also my S-Curves here on Thingiverse.
Update 04.05.2019: I added 2 more: 2x60 and 2x120
Update 18.08.2019: all the curves are now available with 2 "angle of Slopes" , 0 and 35 degrees