I made these over the summer with my cousin and the actually turned out better than I thought they would. they're pretty simple too.
Here's what you need:
1 plastic Christmas ornament per detonator
PVC pipe to fit in between detonator halves
Grey spray paint
Sharpie marker
LED and Battery pack from Radio Shack
Gray Clay (crayola model magic is what I used)
Button Greeblies
1. cut the ornament in half and sand down the hook socket neck
2. mark out and cut the notches in
3. cut PVC to a length that fits your ornament
4. drill the hole for the LED and place battery pack in the PVC
5. drill 3 holes in the back of the PVC pipe for the button greeblies
6. Run wires through greebly holes
7. sculpt the switch out of the clay to cover hook neck hole
8. Connect wires and glue together
9. paint
This video helped me alot: