Simplified Duplo tracks

This is my very first project in OpenSCAD. Tracks are designed from scratch, the goal was to shorten print time and to increase bottom surface - to avoid delamination of ABS from the hotbed.
One try was attempted to print the straight track, but was unsuccessful due to printer failure - new attempts will follow next week.

Note: you need OpenSCAD 2016 to modify/render the curved track, 2015 has no angle parameter in rotate_extrude.

2016-03-09: All files were updated (actually, the old curv