- maybe not as efficient as a full circle. NOT IMPLEMENTED YET. Quality = "preview"; // ["fast preview", "preview", "rendering", "final rendering"] // Top radius of the rail + a safety margin // margins from edges h_margin = hole_dist_side + thickness; working_height = height / 2 + hole_diameter + hole_margin*2; cutout_width = board_width - (side_margin * 2); cutout_height = board_height.