" Silver solder the nuts together: This will allow electricity to pass through the wall (nuts) of the flashlight, and will make the whole thing much more durable. That way you won't need to worry about the positive wire (the red one) getting entangled in the spring, and will create a much cleaner finish.
Use heat-shrink tubing instead of electrical tape: My best guess is that the insulation of the LED is what causes the loose connection. Heat-shrink tubing would make it much cleaner and would probably eliminate any short circuits.
Use bigger Nuts: Bigger nuts would make everything much easier to work with, and you wouldn't have to drill them out for the button cells to fit inside. "
With this Flashlight, I used bigger nuts and heat-shrink tubing, and it really did turn out much better. I didn't want to buy and learn how to use silver solder, but I bought some glue better than Gorilla epoxy, which turned out to be perfect.