Anyone who’s ever had to draw a straight line freehand knows how tough that is. Now this will be a piece of cake with the Constrained Ball, a cool drawing aid by Korean product designer Giha Woo.

Attach any pen and you’ll draw like a pro. This simple device is fitted with a rubber gasket and provides control for the writer to smoothly draw straight across. It even measures the length of the line as you go with a measuring wheel. Made of a flexible rubber material, this cool gadget will let you draw vertical and horizontal lines, as well as 45° angles, perfectly. Where was this device when I was in school?

This invention is regarding a method to draw straight line without using ruler. Normally, ball point pen freely rolls in accordance with a ball that located at the tip of pen. This device is to apply a controlling condition to a ball in order to rolls to only one direction. Let’s draw a straight line with a ball that has restrained with directivity.

Tags: gadget, concept, constrained+ball, drawing+gadget