Introduction: Firefly Forest

Hi! Welcome to my second instructable. I liked sharing the previous one so much, I decided to have another go!

OK, after finishing the Borg Kjoeb I was left with another PumLantern kit with only green LEDs. What to do? I decided to try my hand at some diorama building, as I now had all these paint thingys from the previous build. Having never made a diorama before, there would be plenty of new stuff to learn!

Let's go!


For the frame and the base

  • IKEA picture frame BAS (not sure if they still sell these)
  • foamboard (0.5 cm thickness)
  • cardboard

For the diorama

  • expanding insulation foam stuff (use in a well ventilated area)
  • wall filler
  • acrylic paints (I mainly used greens and browns)
  • some really really dry twigs (not sure if "real" wood can be used, time will tell)
  • decorative moss that you can buy at the hobby shop
  • some small gravel stones, ground coffee or sand and other bits and bobs

For the fireflies

  • optical fiber: I got mine from a cheap toy, and simply cut the strands that I needed
  • pumlantern kit from Solarbotics
  • electrical tape
  • hotglue
  • tacky glue (white glue)


  • soldering iron
  • exacto knife
  • drill
  • infinite patience or beer

OK! Let's build!

Step 1: A Frame Within a Frame

I made an internal frame that would fit snugly within the BAS wooden box. The sidewalls are made of cardboard. The base and the back are made of foamboard. I left a bit of space at the back to fit in the LEDs later.

After some fiddling, it fitted perfectly within the box.

Step 2: Foam Party!

So, I needed to have a place to hide the electronics in. That's where the expanding foam stuff comes in.

I basically made a blob out of expanding foam that you normally use to insulate your house. Then I cut the piece so that it fits inside the box.

The electronics fit inside the cutout space inside the foam.

Step 3: Fill in the Gaps

Time to smoothe out the foam stuff. For this step I used wall filler. Mine had a structure to it, but you can use any wallfiller I guess. I thinned the filler with some water (waaaaay too much, so add small amounts of water at a time - don't be like me)

I also painted the base in foresty colors, and glued a forest backdrop to the back.

After the filler had dried, the piece (of course) did not fit into the box anymore. No worries! Just cut a slice of the backpart until it fits

I also painted the "blob" with acrylic paint. Turns out that brown basically made it look like a piece of.....

Yeah, I repainted it with different shades of green after that (sorry, no pictures).

Step 4: Frustrations Part 1

Oh my.... making a fake forest is FIDDLY WORK!!

Tacky glue really behaves differently than the superglue I'm used to. In the end it worked, but it really took some getting used to. Especially the longer drying times!

In the end, it turned out OK and I was pretty happy with it.

Step 5: Frustrations Part Deux

And now... the optical fiber. As you can imagine... this was the most fiddly of fiddliness...

With a needle and a bent paperclip I pricked holes in the places where I wanted the indvidual fibers to go.

And then simply threaded the fiber through the holes. So far, so good!

Glueing the optical fibers into place is best done with tacky glue. Hot glue melts the fibers if you're not careful!

Step 6: Let There Be Light!

The Pumlantern has 4 LEDs, so I had to make 4 separate groups of optical fiber. Fun!

I randomly made groups, and checked in between with an LED if the groups looked OK on the front.

Time to assemble the PumLantern circuitboard as well! Do not attach the LEDs to the board as they need to be away from the circuitboard, so that they can be attached to the optic fibers later.

First put some heatshrink tube around the four groups. Then, cut the fibers to the correct length.

With a second piece of heatshrink tube, I connected the fibers to the LED's. Not all fibers survived the heatshrinking, unfortunately.

Attach the LEDs to the back of the foamcore with a dab of hotglue. Let the glue cool down a bit before you press the LED with the fibers in saves you your fingers and the optical fibers.

Step 7: Testrun and Some Problemsolving

After attaching the LEDs tot the backpanel, it was time for a testrun. I drilled a hole in the frame for the solar panel wires. Then I slid the whole thing in and it still fitted! Yay!

Unfortunately, there were some major light leakages that needed to be fixed. The LEDs that were provided by Solarbotics are exactly what they say on the box... Ultra Bright LEDs. So I had to dimm them down a bit.

I wrapped the LEDs in black electrical tape. To make sure there was no light leakage from the top, I also created an electrical tape "lightdam" to block the light.

Then, put everything back into the box, and tadaaa DONE!

Oh, yeah, you do need to solder the solar cell to the wires of course. But then you're done!

Enjoy your own personal forest with firefly lightshow!