Kiteboard deep concave with OPENSCAD mod files.

The final STL file is for DELTA printing, most other printers won't go high enough unless you make it really small. This is a 1/10 scale 1400mm x 400mm board.
I developed the surface with tweaks to my vase building program. The base cylinder is wider at the ends and deformed to sway left the closer it gets to the middle in height. As a consequence, the vertical surface slice I have chosen has a little less concave towards the ends (easier turning). Also, I've got two scales of sinewave playing