Holes accept M3 threads, but are not threaded (simplicity).
Features:
Required Parts:
Only three non-printed items are required:
Item
Type
Battery
CR2032
LED
5 mm
Hex cap Screw
M3x5
You may need to add a piece of tape on the battery to keep the lead from touching when the button isn't being pressed.
Assembly:
Start with the bottom piece - it's the side marked with a + symbol - this is the positive side.
Slide the LED into the slot, with the long lead (anode, a.k.a. positive) on the bottom.
Insert the battery between the LED leads, with the positive side down.
Add tape if required.
Adjust the top lead so that the LED only lights when the end of the cathode (negative) lead is pressed against the battery - this is the most fiddly part of the process, and may take several tries.
Slide the top piece - with the button gently downward on top of the LED/battery assembly. The LED should light up when the button is pressed, and not light when the button is not pressed.
Insert the M3 cap screws into the top piece, and tighten the threads into the bottom piece. There are no threads in the printed part.
Add a Key Ring. The final assembly should look like this: