Infinity Mirror Electoplated Hair Stick

What do you give someone with gorgeous, long hair for a present? A hair stick to tie her hair up with, of course!

And if you are an electrical engineering student, you make it to glow, because why now?!

Originally, I planned to carve the 2-prong hair out of wood, then put a custom printed circuit board (PCB) with LEDs on the top. However, somewhere on Instructables I got the idea use an infinity mirror instead. A friend suggested 3D printing the hair stick and electroplating it with copper for a metallic finish.

So, that's what I did, and here's how I did it!

Body of Hair Stick

• 3D Printed Disks - See attached CAD File
• 6" US Size 1 Double Point Stainless Steel Knitting Needle - Amazon

Electroplating

• Nickel Conductive Paint - Amazon
• Copper Sulfate Pentahydrate - Amazon
• (2x) Alligator Clips
• Glass or Plastic Tall container
• Piece of Copper
• (2x) AA batteries

Infinity Mirror

• One way mirror window film - Amazon
• (1x) 1" mirror plastic disk - Amazon
• (4x) 1206 SMD LEDs - Amazon
• (1x) 330Ω Resistor
• (2x) Jumper wires
• (1x) CR2032 Battery
• (1x) SPDT Switch
• Miscellaneous Wires

Tools

• Hot Glue
• Soldering Iron
• Scissors
• Wire Strippers
• Stirring Implement
• Tape
• Clear Acrylic Spray Coating
• Heat Shrink Tubing (Optional)
• Super Glue (Optional)

• Copper Tape (Optional)

The first step, is getting the disk 3D printed. Fortunately, I was able to use a friend's filament printer and of the two copies I had printed, one was sufficiently clean to use.

The first CAD design was made for the wrong size LEDs (about half the size of the parts actually I had, oops!) So, I made some modifications with sand paper and promptly updated the design files to fit the 1206 surface mount LEDs. The updated size has not been tested, but is linked here:

OnShape Full CAD

I also designed a back piece, which didn't get printed for this iteration. If you use it, please let me know in the comments how it goes!

I sanded the part down to smooth out some places where the print had gotten messed up and to create a rough surface for the nickle paint to bond to. Cleaning off the dust with soap and water, I moved on to the nickle painting.

Since I didn't get the back piece printed, I instead used a plastic milk jug and cut out a piece of plastic the size of the back. I then sanded it to rough it up like I had with the printed part.

This isn't a necessary step if you 3D print the back piece, but since I haven't tested if the CAD file works correctly, proceed at your own risk!

The purpose of painting the plastic with nickle paint is to make it conductive so that the electroplating will work.

There are warnings posted on the nickle bottle says it is Very Toxic. So, I went outside and made sure to keep the paint from touching my hands.

There is no need to paint the knitting needles, as they are stainless steel which conducts electricity, albeit not well. It seems to conduct about as poorly as the nickle paint, so it worked well to have a somewhat conductive metal next to a somewhat conductive paint.

Be careful to only paint where you want copper! Since copper is conductive, I made sure to avoid painting the inside of the cavity where the battery and other wired connections would be.

I had to do a few coats (3-4), letting it dry in between for both the 3D printed disk and the back piece.

To prepare the solution, I was not very scientific and mostly did trial and error to get a good water to copper sulfate ratio.

Make sure to use a glass or plastic container/stirring instrument for your mixing.

Note: There are all sorts of other methods to copper electroplate such as using lemon juice or vinegar. I suggest digging around on Instructables or YouTube to find a tutorial suited for your specific requirements. If you encounter problems, I also suggest looking at other tutorials, as I am no expert.

What I did:

I was lucky to be able to use a scientific stir plate to help mix, but it's not necessary. Just use a plastic spoon or whatever you have on hand and make sure the crystals all dissolve.

Its tricky to get the concentration right and if you get it wrong, you either don't see any plating or you end up with a black, burnt looking coating on the surface. The light blue color solution is not concentrated enough, so I added more and tried again until it became the darker color which worked better.

Now comes the fun part!

I tried using different numbers of AA batteries to get the electrical supply correct. In the photo, you can see 3 batteries connected in series (the + end connected to the - end of the next battery).

Using alligator clips, the positive end is attached to the piece of cooper and the negative is on the hair stick itself. The two pieces should not touch in the solution.

The copper plated on in a sort of 'fuzzy' pattern, but these spiky bits could be brushed off easily with steel wool or even a light brush. I had to do a few different passes with the plating to build up a thick enough plate that wouldn't get rubbed off easily.

Overall, the process took much longer than anticipated, most of a day of plating, brushing off the fuzzy parts, and plating again.

After everything has been brushed clean, spray it with a few coats of the clear protective layer to seal everything in. This is especially necessary on the sticks, as you don't want any snags to get caught in your hair.

While the plating was happening, I worked on the LED string.

My initial idea was to solder the LEDs to copper tape. Unfortunately, as mentioned, the cavity in the 3D printed part I designed was too small (for some reason I used 0603 in the CAD instead of 1206 LEDs).

So, I changed tactics and measured then cut the plastic shielding on some jumper wires, creating gaps in the plastic and then soldered to the exposed wires. It was useful to pick two wires that were already attached together at one end, because they were easy to keep aligned.

Be careful that the LEDs are all aligned correctly so that they are in parallel and not biased backwards.

It's always good to test your circuit with a breadboard. With your coin cell battery (with holder), LED string, resistor, and switch, you can breadboard up a simple switched LED circuit like the example here from Java Tutorial.

Once that is working, it is time to attach leads to your battery. I used copper tape and some wire to connect the positive and negative sides of the battery to wires I could use to connect to the rest of the circuit. Just be sure to not short the positive and negative sides of the battery together by accident.

Now, solder together the full circuit. I added heat shrink tubing to make sure that things wouldn't short when they get packed together. Keep the leads short so that everything can fit in the back.

Now carefully lay the LEDs in place in the cavity with the wires sticking out the side in the little grooves.

Now hot glue your mirror in place. Make sure that it is on the back side of the LEDs so that you can see all of the LEDs shining through when they are on.

Next, carefully pack the electronics into the back, behind the mirror. Again, hot glue makes sure everything stays in place.

Cut the one-way mirror material into circle the size of your opening and carefully glue it into place. I used super glue for this to make sure that it would stay in place and wasn't lumpy like hot glue would make it.

The same can be done to fit the back into place and secure it with glue. Be sure to align the switch with the hole before attaching the super glue.

Now you can see the infinity effect when the LEDs are turned on!

Finally, you can wear your custom hair stick! Since the LED light level is relatively low, for best results wear it in darker places like indoors or at night time events (unlike the natural light where I took my photos!)

Future steps I would like to take with this project include adding an ATtiny microcontroller so that the LEDs can blink or even maybe change color based on a programmed pattern. Additionally, it would be nice to add a way to recharge or replace the battery without needing to rip the back off.

Let me know what you think in the comments and if you have a chance to make any of these changes in your own version!