A few months ago I posted my first Hardware Flashlight here on Instructables. Though it was a mediocre success, I loved the concept and wanted to have one that worked. So I thought of all the ways that I could improve it. Here's the list of possible improvements I made for the first Instructable:

" 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.

Step 1: Supplies

Usually I take a picture of all the supplies and tools, but this time I lost track of everything I used, so a list will have to do.
Some of the supplies may vary, as the flashlight could be made in various different ways, with various tools. Parts like LEDs may also have different forward voltages, so resistors my vary.

3 white 5mm LEDs
3 680 Ohm resistors
5-7 stainless steel nuts and 1 stainless steel bolt: The size of the nuts and the bolt depends on the width of your battery. The battery should fit through the nuts very loosely.
1 stainless steel nut a size or two bigger than the rest
1 nut of softer metal (optional): I had to use a softer nut, because I found it too difficult to drill a hole into a stainless steel nut manually. A drill press could easily do the job.
12V A23 or A27 battery
Small battery holder spring
2 5x5 squares of perfboard
Mini tactile switch
Stainless steel switch cap or other part that can be used as a cap (I used a small screw)
Insulated wire

J-B Weld
Soldering iron and solder
Third hand
Drill: a drill press would be ideal, but I used a regular cordless drill by hand
Dremel rotary tool: With a metal cutting wheel and sanding bits
Superglue/ Krazy glue
Needle-nosed pliers
Scissors
Bare Paint
Metal hand saw
Clamps
Heat-shrink tubing

Step 2: Modifying the Parts

To make the bottom of the flashlight, cut off the end of the bolt until only about 5mm of the thread is left.

Drill a 5-7mm hole into the side of the nut that will have the switch. Most drills will do the job, but a drill press would be ideal. To attain a clean hole, punch a marking into the center of the nut, then drill the hole using that center point. Use some oil as a coolant, to stop the drill and metal from overheating.

Saw a small 2-3mm groove into the inside of five of the nuts (including the switch nut). I used a regular metal hand saw to do this. The purpose of the groove is to allow a wire to pass through the battery compartment without blocking it, so the grooves should all line up with each other.

Step 3: The Switch

Sand one of the 5x5 perfboards to a disc that matches the size of the nut. Make the edges of the disc slightly slanted, so that it fits neatly inside and doesn't stand out. To sand the perfboard I used a Dremel 3000 with a sanding bit.
Once the disc is the perfect size, bend the end of the battery spring outwards and solder it to the perfboard. The spring should not be wider than the disc, otherwise the battery could get short circuited.
Once the spring is securely fastened onto the disc, superglue the perfboard disc to the nut. When you do this, check that the two grooves are aligned to allow a wire to pass through.

For the switch, break off two of the leads, so that only two remain diagonally. This eliminates any chances of any short circuits. Solder one of the leads to the spring from inside the nut, and superglue the switch to the perfboard to secure it. Make sure that the switch is easily accessible from the hole, so that a cap can easily be glued on afterwards.

Step 4: LEDs

Sand another perfboard disc as before, but to the size of the larger nut.

Poke the three LEDs through the disc as shown above, and bend the leads outward to hold them in place. Check which leads are the anodes and which ones are the cathodes. Solder the leads to the perfboard, and twist the three cathodes (negative, shorter leads) together. Solder them to a wire and wrap it in heat-shrink tubing. Trim the remaining three positive leads to about 5mm, and solder them to a 680Ω resistor each. Twist the ends of the three resistors together and solder them to another wire. Wrap it in some heat shrink tubing for insulation.

Step 5: Putting It All Together

Pass the two wires through a nut, and solder the positive wire to the switch.

Step 6: Glue

To glue the nuts together I chose J-B Weld. It was recommended to me by several people and websites as an adhesive to glue metal to metal, and I was not very happy with the epoxy I used last time. Glue together the front part of the nut, up to the switch (don't do the Front nut yet). I held them together using wooden stirring rods and clamps. Let the glue dry for at least a night (about 15 hours).
Shorten the positive wire so it will fit inside the battery, then strip about 1-2cm of the end.
Then start the battery section. Glue on the remaining nuts one by one, superglueing the positive wire into the groove of each nut. Attach the stripped part to the last nut with something conductive, such as Bare Paint or silver solder (or regular solder if that works).
Leave everything to dry for another 15-25 hours.
Now attach the front nut, and clamp it down to dry. I used a vice to keep it in place, because the small clamps were too weak to keep it still.
Finally, glue in the switch cap. When you do this, make sure that you only apply enough for the area of the switch, or it may get stuck to the nut, making it impossible to use the switch.
As you can see above, I ended up using an A27 battery instead of an A23, because the wire was irregularly glued in, blocking the way.

Step 7: Improvements

Even though it's much better compared to my previous attempt, there are still a couple of things that could be improved about this flashlight.

Silver solder (some of) the nuts: This would eliminate any problems with the wire and the battery compartment, as the wire that ran along the battery could just be soldered to the nut of the switch. It might also give the flashlight a cleaner finish than the J-B Weld, making it look more professional.
Use a drill press with a stainless steel nut for the switch nut: It was quite a disappointment when I realized that my cordless drill wouldn't be able to drill into the stainless steel nut. A stainless steel nut would have made the whole thing look much sleeker and more professional, as the whole flashlight would have been the same material.
Improve the switch: The switch ended up being pretty flimsy and irregular. This would be pretty easy to improve, if I did it again. The switch would simply have to be glued into the nut so that the top is perfectly in line with the hole above it. It could also be done by making the plastic top come through the hole, and then glueing on a shorter cap. The cap was also a bit too big, which was because I needed something that would be big enough for the hole. I should have used a much smaller drill for it.
Keychain/ strap: Even though it would be too heavy to carry around on a keychain, a keyring or a strap would make it much easier to use. With a drill press I could drill a hole into the bolt and add a keychain, but other than that I can't think of any possible way of doing it.

Do you have any suggestions, questions, or ideas? I'd love to get any feedback, or even to see your own if you decide to try to make your own.