1. Make a template.
First you’ll need to choose a pattern for the LEDs,
like a constellation. Most people would choose the
Big or Little Dipper, so I went with Leo — it’s the
best, and it nicely fit the dimensions of the mold
I had chosen. You can search online for a star chart,
use my pattern, or just make one up.
To turn your pattern into a template, import it into
a graphics program (I used Illustrator) and resize
it to fit your mold, leaving a ¼" margin around the
outside. Draw a small circle where each LED will be
placed. Then draw 2 connect-the-dots lines that
touch each LED on opposite sides, one for positive
and the other for negative, making sure the lines
In an empty space, draw a 1" circle for the battery
pack, another circle to fit the switch (mine was ¾")
and a small rectangle for the resistor. Draw more
lines and adjust positions to complete the circuit:
the positive side connects to the positive battery
terminal through the resistor and switch, and the
negative side goes directly to the negative battery
terminal. Place the switch where it will be easy to
reach, and orient the battery holder to make it easy
to change batteries. Make all lines thick and dark so
they clearly show through your first layers of resin.
Finally, draw your mold’s outline ( 3"× 6" rectangle)
around your pattern, flip the image (since you’ll be
using your template from the back), and print it out.
I made 2 copies, with an extra one to refer to and
make notes on. You can download my template at
I rounded up most of these for cheap on eBay, but
you can probably find them all at a craft store, a
home improvement store, and RadioShack.
WARNING: Resin and epoxy are toxic,
dangerous, and can damage many surfaces. Use only
in a well-ventilated area, on a well-protected surface,
and away from kids and pets. Read and heed all
product safety warnings.
Mold for resin Mine was a 3"× 6" rectangular mold
from Castin’Craft, eti-usa.com.
6oz–8oz of clear resin, and catalyst if needed
I used a polyester epoxy, but a 2-part one
would probably be safer.
Resin dyes: black, pearl or white, and additional
colors I used blue and yellow to achieve colorful,
hazy light, plus pearl or white, which helps the
Glitter I used silver holographic and star-shaped
5-minute plastic-approved clear epoxy adhesive
Cyanoacrylate glue aka super or Krazy glue
LEDs I used 10, all 5mm white ( besthongkong.com
part #BEC0501044), but almost any should work.
Lightweight wire Insulation isn’t necessary; I used
24-gauge silver-plated beading wire.
CR2032 batteries ( 2) and coin cell battery holder
mouser.com part #534-1026
150Ω resistor, ¼W or other value from the
calculator at led.linear1.org/led.wiz. This light was
built using a 56Ω , ½W resistor for a 6V source,
3.3V diode, and 20mA current, but LEDs are forgiving, so you don’t have to be too exact, and with
a small array you can use just 1 resistor.
On/off toggle switch
Alligator clip leads ( 2)
Small, strong spring clamps or binder clips ( 5)
Pliers 2 pairs is nice, but not necessary
colored dyes and swirl just until you like how it
looks, then leave it alone until it’s hardened. Mixing
too much loses the effect. If you mess up, pour it
out and try again. The reason you mix colors in this
second layer instead of the first is that the toothpick
can leave permanent marks on the mold.
2. Cast the face layers.
You’ll start at the face of the light and the bottom
of the mold (Figure A, following page). Follow the
instructions to mix up about ½oz of clear resin,
and add glitter or other cosmic debris if you like.
Catalyze it, pour into the mold, and tip the mold so 3. Test and attach the LEDs.
resin covers the bottom and gets up onto the sides Load the batteries into the holder, attach alligator
a bit. Let it harden completely. leads, and use them to test the polarity of each LED;
I added a second layer of blue/green/yellow/pearly it will light when you connect the positive voltage to
colored haze — don’t do this if you want the LEDs to the LED’s positive side and negative voltage to the
appear as sharp points of light. For the haze layer, negative side. Mark the polarity for each. An LED’s
mix another ¹/³oz–½oz of clear resin, add glitter, negative side is usually marked, but you should test
and pour to cover the first layer. Add a drop of dye them all anyway because you’d be bummed to make
and swirl it with a toothpick. Add drops of different- this project and then have the lights not work.