difference() { minkowski() { cube([40,40,0.1]); translate([0,3,1.75]) rotate([90,0,0]) cylinder(h = 3, r=1.75, center = false, $fs=.02); translate([0,0,1.75]) rotate([90,0,90]) cylinder(h = 3, r=1.75, center = false, $fs=.02); cylinder(h = 3, r=1.75, center = false, $fs=.02); } translate([-4,-4,4.5]) cube([52,52,10]); translate([-6.85,-6.85,1]) cube([52,52,5]); translate([27,27,0]) difference() { cylinder(h = 10, r=45, center = true, $fs=.02); cylinder(h = 12, r=29, center = true, $fs=.02, $fn=100); } translate([44,0,6]) rotate([0,45,0]) cube([5,50,3]); translate([50,44,6]) rotate([0,45,90]) cube([5,50,3]); }