Papier mache is an easy way to make rounded objects using scrap paper. There are several different recipes for making papier mache, but all of them use some form of paste or glue and paper. A few have clay added for greater malleability. Some sort of armature or form is needed to create the shape. Balloons make great forms for rounded objects such as hats or bowls. To make a foreman hardhat that can be used as a toy or costume, you will need both kinds of recipe.
Tear paper into approximately one-inch wide strips. Old newspapers or newsprint end-rolls are great for this, but any non-glossy paper will work. Glossy magazine paper can be used, but it will not soak up the glue in the same way as newspaper or even old school papers.
Mix one cup of flour or wallpaper paste powder with enough water to make a thin gravy mixture, usually about two cups. Atmospheric humidity and texture of the powder will make a difference to the exact amount of water. Add 1/4 cup of white glue for most projects, but if you want the product to be a little tougher, add 1/2 cup of white glue. Put some strips in it to soak, and set it aside.
Shred newspaper or newsprint with water in a blender. You will want a ratio of one part paper to two parts paper. Use an old blender that you do not plan to use for food. Shredding paper is very hard on household electric blenders. Use the shred or chop setting on the blender, or use the regular setting in short bursts, stirring the mixture between bursts of blending.
Blow up the large round balloon till it is at least four inches bigger in circumference than the head of the person who will wear the hat. Tie the end firmly so that air will not escape. Layer the strips of paper that have been soaking in the glue in a criss-cross pattern over the balloon covering an area similar to the area that would be covered by a hat on someone's head. Set the balloon and paper aside to dry.
Add another layer of paper strips to the first after it has dried. For a sturdy hat, you will want four or five layers of paper--or maybe even a few more.
Make a paper clay mixture. Mix one cup shredded paper with one cup of dryer lint and 1/2 cup of air-dry clay powder. Add one tsp of oil of wintergreen. This helps keep the mix from moulding and also covers up the dirty sock odour dryer lint clay always seems to have. Add enough of the water, flour and glue mixture from the soaking bowl to make a malleable soft dough. When you have a sturdy cap of paper layers built up on the balloon, use this dough to create a brim, the little ridge markings that are characteristic of hard hats, and any other raised features you might desire. You might need a little brushing of white glue where the paper clay and the papier mache cap interface to make sure the clay parts don't fall off. Let the clay dry.
Add a final layer of paper, moulding it over the clay features. Let it dry.
Pop the balloon and remove it after the clay has dried. Trim any ragged edges with a craft knife. Use the gross grain ribbon to make a band that will fit around the wearer's head. Criss-cross ribbons over the top of the person's head, and sew or staple the ends to the band. This will mimic the safety bands that make the impact cushion under real hard hats. Sew a button of lint, scrap paper or scrap cloth to the spot where the bands intersect on top of the head. Glue the button to the underside of the hat.
Paint the hat in any desired colour. It is now ready for imaginative play or for use as a stage prop.
A wig holder would be really helpful for this process if you can find one in a size similar to the intended wearer's head.
This hat is a toy. It is not intended for use as safety gear.