3D Printed Outside Double Curved Rails

[Super]

This fellow has created outside double curved rails with 3D Printer. It looks like the 3D Design is available from a place like Shapeways  but I am not sure. Nice work but I am not sure if these are printed as one piece or you have to make an upper and lower, glue them together for use in either direction.
https://translate.google.com/translate?s...%2F6433%2F