side lobe trim

envelope.asy

@@ -99,6 +99,11 @@ if (with_labels) {
 	label("$CB_2$", cb2);
 }
 
+// We do not make the envelope fully symmetric, instead we trim the side
+// lobes near the cover.
+cr1 = (corners[0].x, sqsz);
+cb2 = (0, corners[3].y);
+
 // Draw the cutouts
 draw(cl1 -- corners[2] -- cl2);
 draw(cr1 -- corners[0] -- cr2);