Glue little papers
It is the simplest technique and the results can be stunning. You cant use japanese paper or silk paper but you can also use napkin paper or any light paper (some magazines, newspaper) paper. You cut or tear apart the paper in tiny pieces. If the paper is sleak or quite strong, you must make really tiny papers.

Then you glue with fix N glaze glue (napkin applique glue)

You can use plain paper en decorate afterwards with glitters, crayon, painting, mini stencils, mini stickers or painting

You can also use ornated paper (see right picture.

Glue ornated paper
For instance japanese washi paper or chiyogami (origami paper).
Measure the egg and cut a rectangle whose length and width exceeds the egg's dimensions by 1 or 2 mms.

Then fold the rectangle and cut 8 mm strips. Stop cutting at 7-8 mm from the fold.