$fn = 20;
through = 20;
d = 4.5;
e = 0.01;

function midxy(a, b) = [(a[0]-b[0])/2, (a[1]-b[1])/2, 0];
function centerx(w) = [-w/2, 0, 0];

module rcube(s, r=2) {
	hull() {
		for (y = [r, s[1]-r]) {
			for (x = [r, s[0]-r]) {
				translate([x, y, 0]) {
					cylinder(r=r, s[2]);
				}
			}
		}
	}
}

module sixmount() {
	pad = 1.5;
	m = 3;
	ow = 10;
	oh = 6.5;
	s = [ow+3, 10, 4.5];
	color("grey") {
		translate(midxy(s, [ow, oh, 0])) {
			translate([m/2, m/2, -through/2])
				cylinder(d=m, through);
			translate([ow-m/2, oh-m/2, -through/2])
				cylinder(d=m, through);
		}
	}
	translate([-pad/2, -pad/2, 0])
		rcube(s + [pad, pad, 0], 1);
}

module midmounts() {
	m = 2;
	ow = 18;
	oh = 6.2;
	h = 3.2;
	w = 7.5;
	for (y = [h+m/2, h+oh-m/2]) {
		for (x = [-ow/2+m/2, ow/2-m/2]) {
			translate([x, y, -through/2]) {
				cylinder(d=m, through);
			}
		}
	}
	for (x = [-ow/2+m/2, ow/2-m/2]) {
		hull() {
			for (y = [h+m/2, h+oh-m/2]) {
				translate([x, y, 0]) {
					cylinder(d=w, d);
				}
			}
		}
	}
}

module sixmounts() {
	d = 0.5 + 37 + 3;
	ang = 26;
	translate([d/2, 0, 0])
		rotate(ang, [0, 0, 1])
		sixmount();
	translate([-d/2, 0, 0])
		mirror([1, 0, 0]) {
		rotate(ang, [0, 0, 1])
			sixmount();
	}
}

module crossbar() {
	s = [45, 10, d];
	translate([-s[0]/2, 0, 0])
		rcube(s, r=1);
}

module bar() {
	w = 100;
	d = 16;
	h = 10;
	t = 3;
	r = 2;
	translate(centerx(w)) {
		hull() {
			translate([r+d, r, 0])
				cylinder(r=r, t);
			translate([w-r-d, r, 0])
				cylinder(r=r, t);
			translate([0, d-r, 0])
				cube([r, r, t]);
			translate([w-r, d-r, 0])
				cube([r, r, t]);
		}
	}
	translate([0, d, 0]) {
		translate(centerx(w))
		cube([w, t, t+2]);
	}
}

module assembly() {
	module cutout() {
		sixmounts();
		midmounts();
		crossbar();
	}
	difference() {
		bar();
		translate([0, -e, 2])
			cutout();
	}
}

assembly();