Four fours clock

I was inspired by [this physicist's clock](https://www.thingiverse.com/thing:2874745) but some numbers there seemed arbitrary and lacked an overarching theme. I remembered the math puzzle of ["four fours"](https://en.wikipedia.org/wiki/Four_fours): write all numbers from 0 to 10 with exactly four fours, and using the four arithmetic operations; or from 0 to 20 allowing for square root. I typeset the math expressions in LaTeX.

The size is 25 x 25 cm with a hole for the standard clock kit shaft. If you cut on a bigger size, remember to keep fixed the size of the shaft hole.

I cut the face from 3mm plywood on a CNC router to avoid charred edges and engraved on the laser cutter. I tested several clock kits and settled on [this reliable one](https://www.amazon.co.uk/QLOUNI-Movement-Mechanisms-Mechanism-Replacement/dp/B076F8BDV8). If you use different kits or materials, you may need to adjust the supplies, e.g. if the material of the clock face is too heavy for the shaft on the clock k