Soaking the paper is one cause: the wetter you get the paper, the more the fibers swell, so the more they shrink when the water evaporates.  Flour paste tends to require quite a bit of water.

Try this instead: Use regular white craft (PVA*) glue diluted with 'some' water just until it's easy to spread (the really cheap stuff may be thin enough w/o diluting), paint the glue fairly lightly onto the paper, and press firmly into place. Don't coat the top of it. You just want it to stick, you don't want to saturate it.  Paint another piece of paper, and press it on.  Repeat.  With most papers, three layers should be the limit before drying.  You need enough paper to hold the shape while drying, but not so much that it's difficult to dry.

Once it's dry, check the fit, and if you need to add more layers for strength or to build up certain features, go ahead. Just don't make it so thick all at once that it doesn't dry completely. Dried PVA glue resists becoming saturated all the way through when you add additional layers to a dry foundation. Using flour, the moisture tends to wick into the previously dried layers.

*PolyVinyl Acetate

Sue

That's an interesting idea, David!  I wonder if the foil would stick to the face with Vasoline?

For people in the U.S., 'sugar paper' is called construction paper.

Sue