include <../cad/threads.scad>;

$fn=128;

difference(){
union(){
linear_extrude(4)
difference(){
square([28.5,46.5]);
translate([3.5,3])
circle(d=2.5);
translate([28.5-3.5,3])
circle(d=2.5);
translate([28.5-3.5,46.5-3])
circle(d=2.5);
translate([3.5,46.5-3])
circle(d=2.5);
translate([28.5/2,11.5])
    for (i=[0 : 3]){
rotate([0,0,i*90])
translate([8,0])
circle(d=4);
    }
}
translate([0,0,4])
linear_extrude(20)
difference(){
square([28.5,46.5]);
translate([3.5,3])
circle(r=5);
translate([28.5-3.5,3])
circle(r=5);
translate([28.5-3.5,46.5-3])
circle(r=5);
translate([3.5,46.5-3])
circle(r=5);
}
}
translate([28.5/2,11.5, 8])
metric_thread (diameter=6, pitch=1, length=20);
}