To illustrate what can be done with the BOSL2 library for openscad this can add 3 "diamonds" to the RIGHT, FWD, and TOP direction of a square, with the RIGHT and FWD diamond's corner touching the square on the side and the TOP diamond sitting atop the square:

cuboid([8,8,2]) align([RIGHT, FWD, TOP]) cuboid([5,5,2], spin=45);