Design engineer to create an interlocking backgammon playing surface frame

This project requires the designing and engineering of an interlocking backgammon playing surface frame. This frame needs to hold together with minimal solder and must remain flat. The frame will hold the 3 colors of concrete to complete the frame.
One face of the backgammon board must be the exact outline, without any tabs exposed. The underside of frame can have tabs or connectors.
The points of the frame can be bent, therefore a radius at the point is acceptable. See photo of previous work.
As an example we also make a chess frame which does interlock, however that is a simple grid. The shape of the backgammon points creates more challenge in an interlocking design.