But how to divide that tasty,tasty treat fairly, and avoid arguments...

The usual approach; print something.

This is a simple tool used to mark a circular thing into equal-sized wedges which can then be cut with a knife. The number wedges is imprinted on the top.

1. Download the thing's scad. You will also need bezierconic.scad (thing 8931) (google it...) and FreeSerif.scad (see files associated with thing 9126).

2. Adjust the parameters; "sides" would be the most obvious one, but flange height and length are obvious options. The "locating spike" on the bottom you can probably do without.

3. print it. I suggest solid fill. Print it upside down - you'll probably end up with a mess otherwise!

Notes:

• could be improved with something like triangles on the end of the flanges - these could do marking on harder surfaces.
• the cake is a lie