My wife recently purchased some submersible Led lights with the intention of placing them into an 'empty' Bombay Sapphire Gin bottle.

Not being shy of a challenge I set to work acquiring the target bottle!

The rest of the Instructable documents how I managed to shoehorn the lights in.

Step 1: Choice of Battery

My wife placed only one design constraint that batteries were to be used. ie. no external supply or wires.

Oh, and if that wasn't bad enough, she didn't want to be able to see the batteries!

I researched many different types of cells and battery technologies even induction supply.

I finally decided to use the CR2032 as in the original product since it gave best bang for buck and was by far the simplest solution.

This meant that I had to use the 70cl bottle as the diameter was just wide enough to accommodate the two batteries and a circuit board.

So as to allow for battery replacement/maintenance I pared down a single CR2032 battery holder to the absolute minimum and modified it to allow two cells to be fitted.

Before and after shots given above.

Step 2: Production

Once battery selection had been made and holder acquired I set to work making a mechanical framework to secure the component parts in place.

To produce a sturdy mounting bracket I created a template from one of the CR2032 cells which was a perfect facsimile of the internal diameter of the bottle neck and cut an aluminium bracket upon which the on/off switch, battery carrier and circuit board could be mounted.

The bracket was fixed in place under the bottle cap with M2.5 screws. I had to file two flats on the screw heads so that the screw top would locate in it's original position when fully secured on the neck of the bottle.

In order to utilise the available space the batteries were fitted upside down in the holder this was to allow the natural curve of the battery top to better fit the internal diameter of the bottle neck (my wife's idea, Kudos!). To prevent this non-standard fitting shorting out the battery terminals I placed a very small strip of Kapton tape under the clip. As I am forgetful I also engraved a '-' sign on the battery clip so I don't forget to put the replacement cells in the correct way round in the future.

Once assembled I soldered all the parts in place and added a 150R 0805 SMT load resistor, as used in the original.

I cut the aperture in the aluminium cap with a scalpel to maintain good, clean edges as the metal is pretty thin and deforms really easily. Actually I went through around 10 blades in total, cutting through the underlying plastic. I finished off the fixing holes with a Dremel.