Made to put an easy to hold handle on a protest sign. Made large to accommodate winter gloves. Can be scaled down slightly.

If using a large foamboard sign, do not attempt to hot-glue onto sign without using the 2-ply inlay method. The wind will rip the foam out of the sign and you'll have to run for your sign.
On smaller 1 ply foamboard signs, carefully score & remove the paper where the handle is going to be placed. Failure to do this will cause the handle to rip the paper off for you.

I recommend this method for using this handle on foamboard sign:
Items: Hot glue, 2 pieces of foamboard, an xacto knife or sumn.

On one of the sheets, mark and cut out 2 squares so the handle can fit snugly inside them. Place those squares in the middle of the sign.
Hot glue the 2 sheets of foamboard together to make a 2 ply board. Have a friend help with large full-size signs. Make sure to secure the middle where the handle will be well.
You can run hot glue on the outside edges of the board and use something to flatten it over to help overall strengthen anywhere that was missed.
Carefully score the paper on the bottom of the hole and remove the paper. Try to only score the paper and not cut through damaging the foam.
Fill up the holes with hot-glue and inlay the handle into the holes, and then use something to flatten and smooth any run-off over the handle to strengthen.