Thin Profile Light-up Animal Pendant

For the latest work by performance artist Deke Weaver, "Wolf" (part of his lifelong project, "The Unreliable Bestiary"), I have been put in charge of creating fashionable threshold objects which bring audience members into the performance. We created 600+ laser cut medallions, along with a smaller batch that light up, to give out to people attending the free performance (if you are around Urbana, Illinois, you should check it out!).

In the design and research of this project, I learned a lot about the bonuses of incorporating soft-circuit methodologies in an end product which is technically rigid. I also learned techniques for two-sided laser printing, and the manipulation of small electronic components like SMD LED's.The performance is happening in early September, and we just came up with plans to do this at the beginning of August, so this was also an exercise in rapid prototyping and deployment.

The whole batch ended up costing me about 30-40 cents a piece including all the R&D. Make sure to get more materials than you absolutely need to account for screwups.

Materials

• Birch plywood 1/8th inch
• Waxed Linen String
• SMD LED's
• CR2032/2016 3V coin cell batteries
• Conductive Thread
• Conductive Stretch Fabrice Neoprene

Equipment

• Hot Glue Gun
• Access to Laser Cutter
• Soldering Iron + Solder
• Sand Paper

Deke sent me a little JPEG drawing of the original design of the wolf head. I brought it into illustrator, ran the trace object tool on it, and simplify it a  very tiny bit. From there, I made several iterations on this original idea. I added an extra hole at the top of the pendant so that when strung it would lie flat. We also tested out different designs such as having the wolf-face cut out and a half-moon design.

Like most laser cutting, when you make your design in illustrator or corel or an open source alternative, Inkscape, you need to separate your design into parts you want to raster etch (such as the wolf's face) and parts that will be entirely cut out as a vector cut (like the border, and the holes for the lanyard).

We tested out several iterations of designs for the medallions, concerning shape, type of wood, sizes of holes, border sizes, power levels. We also tried many techniques for imaging the wolf face on the front. I tested out several differnt ways of staining the wood (spray paint, balsamic vinegar, steel wool and vineger) to increase the contrast with the front. We eventually went with a natural etching into raw 1/8th inch birch or plywood. This iteration is all very important though, because all sorts of unexpected things will happen with the laser cutter. This will be especially true when creating something in such large quantities.

For some reason whenever people see one of these medallions hanging around a neck, the VERY FIRST thing they do is flip it over to see what's on the reverse side. I figured it would be a good idea to put something back there. Since these will be given away during Deke's performance, I figured it would be nice to have credits printed on the rear to let people remember years from now where their cool wolf pendant came from.

Even if I had not already cut out the medallions, it would be difficult to register correctly laser etching on two sides of the wood. Thus I went for a design that would work regardless of how it was printed on the backs of the medallions. It just repeats the information over and over on a shifted grid. So no matter how it was sliced up, the information would all be included there. It was tricky to not make the text too small however, since there is a limit on the resolution and readability of the laser etching. A font of 7pt seemed to be the lower limit on my Full Spectrum Laser Cutter.

Sometimes, there may be tiny pieces of wood stuck in the holes you cut out. A nice pokey instrument like a dental tool (you can get these at home depot) works great for popping them out.

Next take your string, put it through both holes, and there you go! You have your own nice non-electric medallion. Check out the later steps for making the light-up version!

First before I discuss the steps that I eventually went through, I would reiterate the importance of iterating and experimenting with your design. Your etched image, or wood might reflect or absorb the light differently, and maybe there is a different look you are going for.

I first experimented with using different types of LED's and on different types of lighting for the pendant. Some were just lit from behind. Some were lit inside a small indentation that was cut in the back (to give it a more jack-o-latern type, diffused glow), and some were shining through a hole bored all the way through.

To let the LED shine through, we need to make one small alteration to the illustrator design, an eye hole. We put a small (.01 inch) hole over the eye where the laser will vector cut all the way through. 

I followed Leah Beuchley's idea for adding crimp beads to your SMD led's so that you can tie conductive thread to them. http://web.media.mit.edu/~leah/grad_work/diy/diy_tank.html

I wanted my LED crimp tubes to be oriented the other way, and her technique wasn't working out for me that well (the beads kept sticking to my soldering iron). Another problem for me (too messy i guess), was that my solder kept jumping the gap and over to the other side of the LED, which would short the whole thing. So instead here was my technique.

First set one of the medallions on top of half of the LED. This would keep it weighted down, in place, and prevent solder from getting on the unwanted side. Then I brought the crimp tube on the soldering iron up to it, dabbed a bit of solder on and presto! Half your bead is complete. For the other half, I strung a bunch of the half beads onto a peice of solder, and went down the line adding beads to the sides. Worked well!


*Though I just now saw this idea which seems GREAT from carleyy: https://www.instructables.com/id/LED-Bead-Jig/?ALLSTEPS

Before we go much further, and glue them in and everything, you want to spot check your soldering. This is super easy! Set your multimeter to continuity mode (the beeping mode). Put the + side to the cathode side of the LED (left of the arrow), and put the - side to the point of the arrow. You might not get a beep, but your LED should light up from just the small current provided by the multimeter!

Check through them all to make sure your soldering is good!

To help get my slightly too large conductive thread through the beads, my first step was to make a very nice little threading tool.

Just take some wire-wrapping wire, strip it, and then twist into a nice loop. Using this I strung a line of thread through one side of all the conductive beads. I tied these off with a triple knot, chopped them with plenty of extra hanging string, and then did the same for the other side.

Using the clear-cut eye hole as a guide, we need to cut out an indent in the back of the medallion to put our LED bead into. Place a bead into it to make sure you went deep enough. Don't go too deep or else  you may cut into the front design.

Lay down a small blob of hot glue on the rear side of the eye hole. Line up your SMD LED and fix it in place.

It's usually a good idea just to check it again, before we go too much further. You can check it with a battery!

Next we will put a layer of hot glue over the positive side of the LED and its bead so that when the battery slides in, we won't be touching this part. I was pretty messy at first, but i got better. Anyway this part will be under the pouch. The main thing is to try to not have your hot glue too bulgy.

This great idea was taken from Plusea's Kobakant website, "How to Get What You Want." They had a nice design idea for a stretchy battery pocket for clothes or fabric. http://www.kobakant.at/DIY/?p=4432

My design had to be modified to be attached to a hard surface with hot glue (instead of stitching it onto fabric). I also added a notch at the top to make slipping the battery in easier, as well as holes around the three main edges to easily tie conductive thread through (in case you aren't sewing through it, and just want to tie your conductive thread to it.)

Use the laser cutter to cut out dozens of these from a little sheet of your conductive stretch fabric.

You will tie the positive (+) side of your LED bead to the holes on the side of the pouch (the one that you glued over to insulate it from the battery). Use some tweezers, grab the string, and then just jab the tweezers themselves through the hole.

Next, put a light trim of hot glue around the edges and stretch it over the back of the medallion. You want it to be taught, because it is what will be holding the battery in place.

Just slide the battery in, and wear it out on the town! You can also use these medallions on your bike. I had a couple of blank ones from a laser cutter screwup and I drew different designs on them.

I just shipped off the box of 600+ to Deke for the performance in september! If anyone is around Urbana Illinois, you should check out his amazing performance! It's free!