Crayons---google "crayon artist" and take a look at some of the fabulous portraits and pictures Don Marco has drawn...using good ol' Crayolas
Glue...great idea...never thought of it, but bet it would have helped when doing my Sunbonnet Sue that I struggled to hold the pieces in place....
Whatever works...for whomever....all artist, us quilters included, have their methods and mediums. Let's not disparage another's creativity. Sometimes something beautiful comes from the simplest things!!