$fn = 64; eps = 0.01; intersection() { union() { difference() { union() { intersection() { cylinder( h = 3, r = 30 ); translate( [ -30-eps, -20, -eps ] ) { cube( [ 60+2*eps, 40, 3+2*eps ] ); } }; cylinder( h = 6, r = 24 ); } translate( [ 0, 0, -1 ] ) { cylinder( h = 8, r = 9 ); } // holes for the pegs from the super translate( [ 12, 12, -1 ] ) { cylinder( h=8, r = 3 ); } translate( [ -12, 12, -1 ] ) { cylinder( h=8, r = 3 ); } }; // make the cutout smooth, so plants won't get hurt translate( [ 0, 0, 3 ] ) rotate_extrude() translate([9, 0, 0]) { circle(r = 3); } }; translate( [ -50, 0, -1 ] ) { cube( [ 100, 100, 100 ] ); } }