16 linextr(-base_th, -base_th + 0.01)
17 square(base, center=true);
19 square(base - 2 * base_th * base_slope * [1,1], center=true);
27 translate([hoop_inner_dia/2 + hoop_th/2, 0])
28 circle(r = hoop_th/2);
31 linextr(-0.1, hoop_inner_dia*2)
32 square(hoop_inner_dia*4, center=true);