The pieces appear 3D when looked at from the side but then 2D when viewed from the top. (Modeled to be roughly the same size as a standard chess set)

Supports are needed on each part. If you make the support pattern spacing large enough (~4.5mm), everything should come off nicely and use less filament. 

The board in the pictures is 10 7/8" x 10 7/8" (27.62cm x 27.62cm) which I laser cut with my makerspace's logo.