This felt inappropriate to post on /fa/ because theyre all retards and wont be able to help.

I've never wanted a tattoo, because I always thought I would outgrow the art I chose, or that seeing the art everyday would make it less beautiful to me and ruin the novelty of the art.

The solution I had to this, was a tattoo that fulfilled a purpose. Something utilitarian like a ruler, or a protractor. Something which is a useful tool, that I cannot effectively memorize.

Now not every utilitarian tattoo is a good one, a unit conversion such as 25.4mm to 1inch is easily memorized, and if I got it tattooed id memorize it instantly, so to me that would be a waste of skin.

So far Ive come up with:
>To Do list
>Ruler
>Protractor
>Empty Excell grids for data gathering
>a blank Cartesian graph with base units of centimeters for plotting data or for measuring 2d area of objects

The requirements for this idea are as follows. A 2d image, which cannot be memorized (or which the memorization is not practical) that can be useful in day to day tasks. Help me think of other ideas which may have utility as a tattoo.