Parts and Crafts is a non-profit family hackerspace in Somerville Massachusetts. We teach kids to tinker, make and play with electronics, crafts, carpentry, computer programming and more. We've developed a series of projects that can be made by and with kids, using readily available materials and supplies. We have launched a Kickstarter to sell these projects as kit subscriptions that we manufacture ourselves, but all of our projects are open hardware, so the instructions about how to make them are available for anyone to use! We plan to make videos, online instructions and instructables about all of our projects.
This is a simple edge lit clear acrylic sign that can be made by kids and adults using simple tools. Clear acrylic traps light using a property called internal reflection in areas that have been cut, engraved, or scraped. Most edge lit clear acrylic projects use lasers or elaborate cutting tools to create the design - this project uses a foam sticker and sand paper. Combined with a simple circuit, this is a project nearly any kid can make their own!
Step 1: What You Will Need
1) A square piece of quarter inch thick clear acrylic with an LED-sized notch cut out of the bottom (see below for how to cut the notch)
2) A 5mm through-hole LED (any color, though with some LEDS like red or yellow, you will probably need a resistor.) Color-changing LEDs work really well with this project! You can get through-hole LEDs at a variety of online retailers - Sparkfun, Adafruit, Amazon, etc.
3) A 2-AA battery pack with leads and a switch (we like the ones from teachergeek the best, but there are others available.) For our kits, we add crimp-on connectors to our projects, but you can always just solder, or failing that, twist and tape!
3) 2 AA batteries
4) Black electrical tape
5) Foam stickers (We buy ours at local craft stores, but anything like this will do.) You can choose any shape you want, but it should be clear what it is from the silhouette (ie. a soccer ball sticker is just going to look like a circle) and remember that the more complicated the shape, the more difficult the sanding job. If you want to make a custom shape, you can use peel and stick foam sheets like these to cut it out from or moleskin (the stuff you use to pad blisters in your shoes (available at any drugstore.) Just remember you need to sand in and around your entire shape, including interior holes.
6) A small piece of fine grit sandpaper.
7) Scissors (for cutting out foam shapes and electrical tape.)
Soldering iron and solder (if you want to solder your connection.)
Hot glue and hot glue gun
Goo Gone (to remove any sticker residue, but you can also just scrape at it with your fingernail.)
Step 2: Prepare Your Clear Acrylic Piece
We make the clear acrylic squares by cutting down large sheets of acrylic into small pieces on the bandsaw and then cutting a small notch in the bottom so the LED will just fit inside. Obviously a laser cutter or CNC router that cuts acrylic could do this in bulk very easily. If you don’t have any of these tools, making the notch in the bottom of the acrylic square could be difficult, but you can do it with a file and some patience or a sharp hacksaw. Trying to cut a notch in acrylic with a hand tool like a pair of snips or a blade will usually result in cracked or shattered acrylic. Having the notch cut into the clear acrylic, so that the LED sits inside, is key to making the edge lit effect work, so don’t just tape the LED onto the side. The notch itself will be hidden in the final product, so it doesn't need to be perfect!
Step 3: Add Your Sticker
Remove, if any, the protective film on your clear acrylic.
The bottom of your piece is where the notch is - the sticker should be oriented that way and a few centimeters above the notch. Stick your sticker on one side of your clear acrylic. You can use any sticker you want, but remember, the more complicated the design (especially if there’s lots of internal cut outs) the more complicated the sanding job. For this project I’ve used a simple heart. The snowflake is an example of a sticker that would look very cool, but is very complex (and was abandoned by the kid who started it.)
Step 4: Build Your Circuit
This is a simple LED circuit, attached to a switched battery pack. As mentioned above, if your LED is red, yellow or orange and requires less than 3 volts, you may need to add a resistor to your circuit. This is easy to do and many of the LEDs we order online come with resistors that are reasonable to use in this kind of circuit. You can learn more about how to add a resistor to a circuit online. If you don’t want to add a resistor, choose a color like blue, white, pink or purple, or, even better, a color changing LED!
First put your batteries into your switched battery pack (flat side against the spring!) Then connect the battery packs two wires to your LED.
Through hole LEDs like we use in this project have two wire legs. One of the legs is slightly longer than the other. This is the positive leg. The shorter leg is the negative leg. Wired battery packs like the ones that we use have two wires, one red and one black. The red wire is the positive wire and the black wire is the negative wire.
Turn your battery pack on (if it’s one of the teachergeek.com ones listed above, you need to push the metal level down snugly into the battery pack to turn it on, lift it up to turn it off.) Be careful when your battery pack is on not to let the red and black wires touch - you will short your circuit and your batteries will quickly get hot. If this does happen, turn the battery pack off.
In our kits, we attach crimped on connectors to our components to make assembly easier, so it’s simply a matter of touching the positive and negative ends to the connectors on the LED to figure out which is positive and which is negative, and then sliding them on in the right configuration. If the battery pack is switched on and you touch one wire to each leg and the LED doesn’t turn on, reverse the wires and it should. Then slide the flat part of the crimped on connector into the receiving end, once for each wire.
If you don’t have crimped on connectors, just strip and twist the red wire onto the longer leg of the LED and do the same with the black wire onto the shorter leg. Remember not to let the legs of your LED touch each other either. You can now solder, for a more robust connection, or, after twisting the wires together firmly, just wrap them with a small piece of electrical tape.
Step 5: Scratch Your Acrylic
Now use the small piece of fine grit sandpaper to sand everywhere on the piece of acrylic that is not covered by the foam sticker. The sticker acts as a mask - it prevents you from scratching where you don’t want to scratch. It’s important to get as close to the edge of the sticker as possible and in all the nooks and crannies. It’s helpful to roll the sandpaper into a tiny, pointed stylus of sandpaper and use that to get into the interior bits of letters, or the corners of shapes like stars or hearts. Kids who do this project sometimes get tired of the sanding, but it’s pretty easy work and the more sanding you do, the happier you will be with the final product. You only need to sand on one side. Sand all the way to the edges and go around and around the lines of your shape. Sand, sand, sand! Sand until all the space on your piece of acrylic not covered by your sticker are scratched up and look white instead of clear. The edges of your foam sticker might get roughed up a bit in the process, but that’s okay, we’re going to pull it off and throw it away.
Step 6: Remove Your Sticker
If you’re satisfied with your sanding job, you can now remove your sticker. It is usually possible to pull foam stickers off without leaving residue, but sometimes things don’t work out that well. Goo Gone is useful for getting the sticker gunk off (beware, the oil of the product will temporarily fill in all the tiny scratches created by your laborious sanding and make it appear, momentarily, that you have ruined your work!) but you can also remove any sticker residue with some dedicated fingernail work. You should see your shape, isolated in clear acrylic, surrounded by gentle scratches.
Step 7: Combine Your Circuit and Your Acrylic
Stick your LED into the notch and spread the legs out along the bottom of the piece of acrylic so they won’t touch. This is a step where hot glue, if you have access to it, would work well. You can apply hot glue directly onto the LED in the notch and then hold it there until it dries, and then hot glue the legs, spread out, along the bottom of the project. If you don’t have hot glue, just use tiny pieces of electrical tape to hold the LED and it’s legs in place, then wind electrical tape around the base of the project, covering the LED. Even if you hot glue it, still add pieces of electrical tape to hide the LED light source, as the final effect is greatly improved if you can’t see the LED source.
You can tape or glue your battery pack to the back of the project to act as a stand, just make sure you can still access your switch (in one configuration, with our battery packs, the lever will hit the acrylic and not allow you to turn it on - the easiest way to figure this out is to just turn the project on and then tape or glue the battery pack on that way.)
Step 8: Turn It On, Enjoy It and Make It Your Own!
This project looks best in the dark! Kids have added this project to other designs to make elaborate bedside lamps. Multiples of this projects could be combined (possibly with a parallel circuit) to make a word or other design. If you do something cool with this project, please let us know! And if you are in the greater Boston area, please come visit our shop and make something with us!