Adding Layers to the Inside of a Paper Mache Pumpkin
If you need to color the inside of the pumpkin or thicken the pumpkin for a more realistic effect or to create strength, use a brush to apply a thin layer of glue to the inside of the pumpkin and add more layers of tissue.
You can make the lid thicker so that it sits on a thin walled pumpkin, by coating the underside of the lid with glue and adding rough layers of paper under the top surface until you create the effect you want. If you keep folding a long strip of paper and gluing in between the folds, you will create a thick layer fairly quickly without softening the lid (see photo). When the underside of the lid is sufficiently thick, use scissors to trim away the added paper layers, back to the original cut lines on the lid of the pumpkin.
Tip to make smoother paper mache, use smaller pieces of paper. Another way to create a smooth surface is to coat the outside with a layer of artist's gesso. This will fill in the cracks and make the pumpkin completely smooth. It will reduce the transparency of the pumpkin if you wanted it to act as a lantern, and of course it will need to be painted (or have acrylic or watercolor paint added to it) as gesso is white.
