Step 1: Building It
All you will need to be prepared in any emergency is an Altoids or equivalent tin, some tiny bottles (the smallest one is from a miniature Tabasco sauce bottle), a tiny ziploc bag, a folding paper cup (about the easiest origami there is), and the stopper cannibalized from a dollar store water pistol. Oh, and of course gin (I favour Plymouth) and vermouth (Noilly Prat).
Drill a hole for the stopper. The diameter will depend on the exact stopper you use – I used a 5/16 bit. Be careful drilling this as you can easily buckle the metal – I started with a small bit and worked slowly up, putting almost no pressure on the drill head. The hole needs to be as neat and round as possible.
Insert the water pistol stopper. And that's it. You are now prepared for any situation that demands a small, warm cocktail.
If only I could figure out a way to ice it...
Step 2: Water Pistols Are Great
This is the water pistol I got the stopper from. Water pistols have all kinds of useful parts which can be hacked for other projects. Stay tuned...