I recently brought a 2nd hand electric guitar (I'm trying to graduate from acoustic) and it didn;t have any potentiometer knobs. Instead of just using some stock stand knobs from eBay, I decided to pimp it up and add my own, custom shotgun shell knobs.

I tried a few different methods (starting with the hardest way first!) until I hit on a simple but effective way to mount them on a pot. The trick is to make sure that the potentiometer is centred on the shotgun shell. If it isn't, the shotgun shell will be un-even on the potentiometer and will have a little wobble when turned. My OCD kicks in when I see that happening.

I've also used these knobs on a amp that I built (check out the images) and also on a couple of homemade synths. They add some real style and actually feel really nice to turn.

Step 1: Parts & Tools

The good news is, you only need a couple parts to make one of these. There is some technique though so don't think it's as simple as sticking a knob inside the shotgun shell.

NOTE: I know that it isn't really a shotgun shell but just the brass cap of the shotgun shell. Brass head though doesn't have the same ring though.

PARTS:

1. Shotgun Shell Shell. I get mine for free at the local gun club. You can also buy them on sites like Etsy.

2. Potentiometer knob - eBay. I found that these ones work very well.

TOOLS:

1. Dremel with a metal cutting wheel and grinding stone. You could use a fine metal saw as well instead of metal cutting wheel.

2. Superglue

3. Hot Glue

4, Hammer

5. Nail punch

6. Blow torch

7. Pliers

8. Fine file

9. Sandpaper

10. Drill

Step 2: Removing the Priming Cap

STEPS:

1. Place the shotgun shell on something like a vice and open the jaws slightly.

2. With a nail punch, place it inside the shell so it is resting on the bottom of the primer in the shell

3. Tap a few times with a hammer to remove the primer. Make sure you keep the primer and you'll need that later

4. Inside the brass cap on the shogun shell you will see some small metal teeth. You'll need to reduce the size of these and in the end remove them altogether. To reduce the size, I find the best way is to use a drill bit slightly larger then the primer hole and drill out the teeth as much as you can. You won't get them all but you'll reduce the size and hopefully remove most of them.

NOTE: Drilling the 'teeth' out isn't100$% necessary. You can just grind the teeth out with a dremal and small grinding stone attachment. Doing this step however, reduces the size of the teeth inside the cap and makes grinding them easier

Step 3: Removing the Cap From the Shell

STEPS:

1. Place the shell in a vice and make sure it's secured well

2. Heat the end up with a blow torch (you could use a lighter if you don't have a blow torch) and heat up the cap for about 5 seconds

3. Place a pair of pliers around the cap and carefully pull off the cap. There should only be a little bit of resistance. Give it some more heat if it doesn't come off first try

4. Leave to cool

Step 4: Removing the Metal Teeth Inside the Cap

This can be a little tricky. You want to remove all of the teeth inside the cap and make the inside flat. However, there is a danger that you might remove too much material and damage the cap. I found that using a grinding stone works excellently. You could also file them out with a small, rounded file but this will take some time

STEPS:

1. Place a grinding stone in the dremel

2. push down onto the metal teeth inside the cap

3. Keep moving it around until all of the teeth are removed and the inside is as flat as you can get it.

4. Use a file if necessary to clean up any rough sections

Step 5: Modifying the Potentiometer Knob

The key part in the build is the potentiometer knob that is secured inside the shotgun shell cap. This will ensure that the knob will fit onto the potentiometer well.

STEPS:

1. Grab the knob and with a pair of needle nose pliers, remove the top metal section.

2. Use a file or a belt sander to clean up the top section. Remove the aluminium on the knob until you are at the plastic section of the knob

3. Its best to secure the knob in the shotgun shell cap with a little bit of superglue before adding the hot glue. This will make sure it is centred. It also helps when adding the primer cap in the next step. Add a few drops of glue around the top section of the knob.

4. Place it inside the cap and make sure it is centred as best as possible. On the top of the knob there is a spiral pattern and you can use this to help centre it inside the cap

Step 6: Modifying and Adding the Primer Cap

To be able to put the primer cap back onto place you'll need to remove most of the section that usually goes inside the cap.

STEPS:

1. Place the primer in a vice to secure it

2. Use a cutting wheel on a dremel (or a fine metal saw) and cut the top section off

3. Remove any burrs with a file. You should really only have the top section left

4. Before gluing onto the cap, make sure it fits. If it does, add a dot of superglue to the top section of the knob and glue the primer top into place

Step 7: Securing the KKnob Inside the Shotgun Shell Cap

STEPS:

1. Check once more and make sure that the knob is centred inside the cap. If not, you might have to give it a tug and break the glue holding it in place. It's important that it is as centred as possible.

2. Carefully add some hot glue to the inside gap between the knob and cap.

3. Keep on adding glue until it is right to the top.

4. Once dried, sand away any excess hot glue so it is flat with the bottom of the cap

Step 8: Add the Shotgun Shell Knobs to Whatever You Want

That's it! You can now add the knob to any potentiometer you want to.

I'm really happy with how they have turned out and with this process, you'll find that the shotgun shell cap is nice and centred.

Now that you have made one you may as well go ahead and make some more. They get easier each time and you'll find that you'll be able to make them quickly the more you make. They only take me a few minutes to make each one now.