Homemade Flashlight, Part III

This shouldn't be this hard

While I managed to get the innards more or less made to fit within the bottle, the electric tape kept adding enough thickness that it was getting really hard to pull it out without the whole thing falling apart. Even though I already intended to switch out the bulb, I decided to rebuild the rest of the battery and bulb circuit from the cap up paying attention to thickness and robustness.

Rebuilding the Insides

Metal cap upgrade

I started by finding the original cap to the bottle and buffing off the ugly sell by date. Lining up the holes was made simple by using the plastic cap as a makeshift jig.

Wrapping the tape around the switch block

As I reattached the switch block to the cap, I realized I could wrap a strip of electric tape between the block and the cap allowing for a stronger grip on the batteries. This created a much slimmer silhouette by dramatically reducing the need for more tape. No more Nic Cage and his VX rocket!

Nite Ize’s retro fit kit to update your old maglite

I pulled a powerful LED bulb that ran off of two AA’s from a flashlight that I already had and replaced the dim green LED I was using for trouble shooting.

Adding the compression of a spring ensured the circuit didn’t break.

While attaching the lightbulb to the batteries, I realized I needed to ensure that the circuit stayed complete throughout the process of taping everything together. I used a conductive battery spring I found in an old remote control to provide some compressive counter force to the tensile force of the electric tape I used to put everything together.

With the updated version of the insides, I was able to get it into the bottle with only minimal grinding of the bottle mouth!

The new and improved naked flashlight

Finishing the Outside

With the inside of the flashlight complete, I continued to develop the housing. The missing component was primarily the focusing cone that directs the light forward and away from the user. Because the housing is made of glass and I just spent days getting the insides to slide in seamlessly, I would have to figure out how to get the cone in through the mouth as well.

I approximated a circle and cut it out.

Sliding a silver mylar cone into a glass bottle from Lucas on Vimeo.

With that out of the way, I added some tape around the neck for a grip and called it a day.

Completed form, fully assembled

See the final shots here.

See other related flashlight postsĀ here.


  1. Awesome. I wonder if it would be as effective if instead of inserting a silver cone you just painted the cone area of the bottle silver?

    1. I think that the light would lose its brightness when it passes through the glass and it hits the reflective part on the other side. I wanted to try and maintain that brightness.

Leave a Reply

Your email address will not be published. Required fields are marked *