6 d_minus = thick/2; // cca 45 deg
13 cylinder(r1 = diameter/2, r2 = diameter/2-d_minus/2, h = thick/2 + eps);
14 translate([0, 0, thick/2-eps])
15 cylinder(r2 = diameter/2, r1 = diameter/2-d_minus/2, h = thick/2 + eps);
20 translate([0, 0, -eps])
21 cylinder(r = center_hole_d/2, h = thick + 2*eps);
23 for (angle = [0:360/side_holes:360]) rotate([0, 0, angle])
24 translate([diameter/4 - d_minus + center_hole_d/2, 0, -eps])
25 cylinder(r = side_hole_d/2, h = thick + 2*eps);