infty = 100;
eps = 0.01;

wall = 1.5;

zip_w = 4.5;
zip_h = 3;
end_wall = 4;

body_w = zip_w + 2*wall;
body_l = 20;

screw_hole = 3.7;

module body() {
	translate([-body_l/2, -body_w/2, 0])
		cube([body_l, body_w, wall]);

	// front and rear
	for (i = [1, -1]) scale([i, 1, 1])
		translate([body_l/2-end_wall, -body_w/2, 0])
			cube([end_wall, body_w, 2*wall + zip_h]);
}

difference() {
	body();
	// screw hole
	translate([0, 0, -eps])
		cylinder(r = screw_hole/2, h = wall + 2*eps);
	// front and rear holes
	for (i = [1, -1]) scale([i, 1, 1])
		translate([body_l/2-wall-end_wall, -zip_w/2, -eps])
			cube([end_wall+wall+eps, zip_w, wall + zip_h + eps]);
}