I always place my gourd on the countertop, and while holding a pencil on a ruler to steady it--turn the gourd around. the pencil then marks an even circle on the top in relationship to how the gourd sits on a table. I then just use an retractable knife to cut it. Many tiny jabs on an angle (with the low er edge facing the inside, so the lid can be easily used as a top again. I usually up 3 grooves in it (2 near each other and one on the other side) so the lid can lock in place and not fall off. Check out the pumpkin, squash forum or Welburn farms for ideas.