Step 13: Encapsulating it Vol III
Turn the card that you have stuck the overlay onto upside down, with the arrow pointing to the bottom right, then stick on the first spacer card with the PVC cement. Put the circuit board in the hole now (use a dab of glue if you wish), and then glue (neatly!) the edge of the piezo disk onto the circular lip. I used some more PVC cement, but would probably be best to use superglue or Epoxy - this item should be held tightly. Then glue the second spacer over the top of the first with some more cement (yours should now look like the picture), and finally glue a blank PVC card to the back.
The overall card thickness is governed by the batteries (1/16" or 1.6mm) - I have added another two PVC cards to the front and back, but you could make these even thinner so that the whole card is approaching this thickness of just the batteries.