infty = 60;
eps = 0.01;

body_h = 4.5;
d_out = 33;
d_in = 15;

module spacer() {
	difference() {
		cylinder(r = d_out/2, h = body_h);
		translate([0, 0, -eps])
			cylinder(r = d_in/2, h = body_h + 2*eps);
	}
}

cube_d = 21;
hole_d = 11.5;
hole_d2 = 13;
side_cut = 1.5;

module inner() {
	difference() {
		translate([-cube_d/2, -cube_d/2, 0])
			cube([cube_d, cube_d, cube_d]);
		// hole
		translate([0, 0, -eps])
			cylinder(r = hole_d/2, h = cube_d + 2*eps);
		// hole - moiddle ring
		translate([0, 0, cube_d/2])
		for (z = [-1, 1]) scale([1, 1, z])
			cylinder(r1 = hole_d2/2, r2 = hole_d/2, h = 1.5);
		// bottom cuts
		for (x = [-1, 1]) scale([x, 1, 1])
		translate([cube_d/2-side_cut, -infty/2, 0])
		rotate([0, 45, 0])
			cube(infty);
		// bottom cuts
		for (x = [-1, 1]) scale([x, 1, 1])
		translate([cube_d/2, -infty/2, cube_d-side_cut])
		rotate([0, -45, 0])
			cube(infty);
	}
}
	
spacer();

translate([d_out, 0, 0]) inner();