On one of the forums I contribute to I was asked about making a papier mache egg with an opening for hiding treasures in - so I set to experimenting!
I tried a few things that did not work, like an inside lip to hold the egg shut - I made it too rigid and it pushed it out of shape. I also found that as I am not so great on the accuracy side that my two halves did not meet nicely - I solved that by adding a small outside lip to hide the uneven edges. Bonus - this also holds the two halves in place nicely.
I am really pleased with the process I worked out and with the final result. It is lined with tulle to make a snuggly place for treasures and treats.Tutorial
For this craft you need two bowls, cling-film, newspaper, white paper, tissue paper, paste, and ribbon.
The two small bowls need to have the same size opening, alternatively you can use just one bowl and make one half first and the second half later. Cover the bowls with cling-film.
Glue strips of newspaper onto the bowl and leave to dry. When it is dry carefully remove the bowl and cling-film and leave it to dry on the inside as well.
Add a layer of white paper so that no newsprint will show through the final tissue paper layer.Use layers of strong packing tape to make a hinge to join the two halves of the egg.
I suggest making a small lip on the outside of one half so that it fits a tiny bit over the other half - this helps hold it together. Finish the outside with a layer of torn tissue paper.
Glue a ribbon to the bottom so that the egg can be kept closed with a bow.
I also have made a worksheet (PDF) that you can print out - http://www.papercraftsforchildren.com/wp-content/uploads/2010/03/tutorial_paper-egg.pdf