The Constrained Ball concept is one drawing tool that might just appeal to architecture students as well as those who want a really, really straight line. Outfitted with a rubber gasket, the Constrained Ball will enable you to draw out straight lines with it measuring the length at the same time. While it won’t mean the end of the ruler is nigh if it were to be released commercially, the fact that you can outfit the Constrained Ball onto various writing/drawing instruments make it all the more appealing. Judging by the size of this concept device, we could probably be looking at it running on a button cell battery, or better yet, a solar panel if there is enough space for one.