Prepare your popcorn flavors and let cool/dry before placing in tins.
Cut a piece of cardstock paper or cardboard that is the same diameter as your popcorn tin, and about 1 inch taller. Fold it in half. Cut a second piece that is half the diameter. Arrange them in the tin so that they are creating equal sections inside the tin.
Fill each cavity with 1 cup of each flavor of popcorn.
Carefully remove the cardboard.
Cover the popcorn tin. If you don't plan to open the tin right away, cover with plastic wrap before adding the lid. The popcorn will keep for about 10 days.