sxy = pi_nom_sz/2 - [1,1] * pi_nom_centres_in;
for (mx=[0,1]) mirror([mx,0,0]) for (my=[0,1]) mirror([0,my,0]) {
difference(){
union(){
linextr(-0.1, pi_mount_z + pi_board_support_z, convexity=1)
rectfromto( pi_nom_sz/2 - 2 * [1,1] * pi_nom_centres_in,
sxy = pi_nom_sz/2 - [1,1] * pi_nom_centres_in;
for (mx=[0,1]) mirror([mx,0,0]) for (my=[0,1]) mirror([0,my,0]) {
difference(){
union(){
linextr(-0.1, pi_mount_z + pi_board_support_z, convexity=1)
rectfromto( pi_nom_sz/2 - 2 * [1,1] * pi_nom_centres_in,