I don't draw many straight lines but when I do I want to use this. Rulers are so Century. Constrained ball is a drawing aid. attached to the pen, this device helps to draw straight lines without using a ruler. designed by giha woo.
I am an Apple user and have been for the last decade or so. I use the generation before the latest MacBook Pro I like Apple products and would be hard pressed to change to anything else at this point in time.