Step 6: Affix controls
Wiggle the extra wires back through their hold and press the controls against the can, then note where the three screw posts hit the plastic. Snip them each down so that the top and bottom of the control panel just makes contact with the can as well as the posts. Then, apply a little superglue to the tips of the posts, press against the surface, and hold.
Now fill in the gaps with a glue gun (if I had know about the TechShop's plastic welder I would have used that, and the extra plastic from the headphones band, instead).
Place the speakers inside the foam, drop the battery into the right muff, and carefully cram the foam into place; you'll have to put it in sideways and twisted into place.
Use a heat gun to shrink the tubing, if you used it, and feel free to paint over the hot glue.