Fit two short plates together

[RalphU (RU)]

Here is how I explained it dividing a circle with a dovetail

How to create a two piece circle with tabs

My laser bed is 20" x 12". I want to create a circle that is 18" in diameter. To do this, I need to split the circle in two pieces that will be 18" x 9", but one piece will have 3 male tabs and the other will have 3 female inserts for the male tabs, so that the 2 pieces can be connected together to form the 18" round. Can anyone tell me how to go about accomplishing this? Thanks!