Preventing warping when printing 3D ABS objects

The biggest issue when printing 3D ABS objects is warping. As an example, this 8 cm x 8 cm bit holder is badly warped. In this example, 5 mm. Adding disks (1.5 cm x 1 mm) at each corners prevents warping almost completely. These anti-warping disks can be easily added on the plater of Slic3r. The printing end result printing is shown on the picture below. 1 cm x 0.6 cm disks also works fine. After trimming the disks, the end result is very good. Warping is less than 0.2 mm. You can download the OpenScad source file along with some rendered files.