What is a type of bead you iron together?

You can only do this with certain types of beads, called Perler beads, or Hama beads. What you do is you put a piece of ironing paper (which comes with the beads) or wax paper, on top of your design. Then with the iron set at medium, you iron the design through the wax paper. Keep the iron there for 10-20 second, or until you have reached the desired effect.