Introduction: LED Throwie Christmas Tree Decorations (No Soldering!)
I made these Christmas Tree decorations using the laser cutter at MADE, the makerspace here in Barcelona.
I added lights by hacking the classic LED Throwie design.The battery (CR2032) sits in a cutout in the body of the decoration and an LED slots in above. No tape, no glue... I like how they turned out.
Feel free to copy, adapt and share, but they are please attribute them: @johnnyforeigner
This work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.
Step 1: Materials List
Some 4mm plywood - I just used some of the scrap that is always lying around in the laser cutting room at Made Barcelona. The different designs are different sizes, but they're all around 100mm diameter.
One CR2032 lithium battery (I bought them at a local "everything for a euro" store, and in fact if you buy them in cards of 5 they are only 0.80€).
Some 5mm superbright LEDs. I bought mine from Bright Components in the UK, but you can find them anywhere. They're really cheap - I paid about 0.10€ each. Green ones and red ones look very Christmassy and work well on the Christmas tree shapes, cool white ones or blue ones are great for stars and snowflakes.
Some decorative ribbon to hang your decorations from is handy. It's about a euro for 5 metres at the same place I bought the batteries.
You can paint them if you like - I used some metallic silver spray paint. Some people at MADE Barcelona have glued decorative wrapping paper on the plywood before cutting it - if you do this, it's best to put the plywood with the paper facing down in cutter to reduce scorching.
Step 2: Design the Decorations
I used Illustrator to design some basic Christmas decoration shapes - trees, stars, snowflakes. I suck at Illustrator so you can obviously make your own if you are more accomplished.
I made a 5 point star, 6 point star, snowflake and a couple of Christmas trees. I imagine you could make a cool Rudolph shape with an LED red nose but I don't have the Illustrator skills to do it. One tip: plywood isn't that strong, so make sure that you leave enough material on the sides of the battery/LED cutout so it isn't too weak. I broke a couple of the straight-edged Christmas trees before I adapted the design.
Step 3: Add the Cutout for the Battery and the LED
Once you've designed the shape, you need to add in the cutout where the battery and the LED will sit.
In theory, CR2032 cells are a standard 20mm diameter, but I found that they vary a little in practice. And of course, the beam of the laser cutter has a width that you need to take into account. You need the circle you cut to be just smaller than the battery so it's a nice tight fit and stays in place without glue.
I started out with 20mm diameter circle but the cells all fell out, so I played around a bit to get to a size that is tight enough so that when you push the cell in it stays in place. In the Illustrator files I've uploaded the diameter of the circle is 19.75mm. It seems good for Maxell brand batteries but the ones I got from IKEA are too small.
Your mileage, (or your laser cutter) may vary, of course.
There's also a hole for the LED. I looked up the standard dimensions of 5mm LEDs and again played around until I had a good fit. The exact size of the LED seems less problematic as it is held in place a bit by sitting over the battery.
Try cutting using the shapes I've uploaded as PDF files. If they don't fit properly, you can adjust the size of the cutout in the Illustrator files I've included.
Step 4: Cut Your Shapes
Our laser cutter at Made Barcelona usually has plenty of scrap 4mm plywood lying around. These shapes are small enough that you can take advantage of material that would otherwise be wasted.
I've also made some with coloured acrylic or frosted white - they both turned out really well although for some reason the hole for the battery in the acrylic came out slightly larger. I guess there's some shrinkage as it melts.
At MADE Barcelona we use PDF files with lines in black, with a width of 0.01mm to cut on our Epilog machine. You should check what's needed for your own machine and adjust the Illustrator files if you need to.
Step 5: Add the Battery & LED
Once you've cut your shapes, place them on a flat surface and gently push the battery into the hole so that it stays in place with friction. Be careful here - 4mm ply is not strong and it's easy to break if you're not careful
Then carefully slide the LED in so that the longer lead is on the + side of the battery.
It should light up as you slide it in and you can just slip it into the slot. If you're lucky the LED will stay lit. If not you may need to jiggle it around a bit. If it's really tricky (or if your LED leads are bent) you may need to add a little convex bend in one of the leads so that the tip presses against the battery).
I found that for the wooden shapes you get the best effect if the LED is just slightly out of alignment with the slot as then the light will shine upwards and light up the stree. For the acrylic material, the LED can be fully inside as it then shines up through the plastic and looks cool.
Step 6: Hang Them on Your Tree!
I used some golden ribbon to hang them on our tree. The superbright LEDs are much brighter than your normal lights and they have a lovely clear light.
Since they have no switch, they'll just stay lit until the battery runs out. Mine are still running after about a week.
If you want save the battery so they last longer or want to switch them off in the day, you can just slip a piece of card under one of the leads. (Thanks to my wonderful wife, Sarah for that suggestion).