Copy-paste this code if you want to have rounded blocks and cylinders in your models.

Rounded primitives for openscad
(c) 2013 Wouter Robers

Syntax example for a rounded block of 20x20x20mm and a 2 mm rounding.
rcube([20,20,20],2);

Syntax example for a rounded cone/cylinder
rcylinder(); // or
rcylinder(r1=15,r2=10,h=20,b=2); // or
rcylinder(15,10,20,2);