8mm rope, 9mm holes, 25mm centre to centre on the holes. 16mm rope for handles, 19mm holes. In Fusion 360 i used a torus shape and 2 cylinders for the cutout of a pair of holes then filleted the edges to make it curved. The width, depth and height of the box were determined by the hole spacing and pattern. Final dimensions of box are 540 x 340 x 260