I was looking to make a gift for a friend's child who is about 15 months old and I was inspired by Ben Finio'sChild's Toy Light Switch Box. Initially, he will probably just play with the light switches, but my friend is a big baseball fan so as his son gets older he can use it to track the pitch count as he watches baseball games with his dad. The darker green section is chalkboard paint so he can keep track of the score as well.
I was trying for something that could be done with minimal equipment. I often see projects on here that look awesome only to find out if I want to do it I'd need a laser cutter. Pretty much the only required piece of equipment for this is a drill. The specialized bit I used can be substituted to a more common spade bit, regular glue can be used if you don't have a glue gun, and if you are uncomfortable with soldering or don't have a soldering iron, you can just twist the wires together and secure with electrical tape. I will also say that this project was my first time soldering and I didn't find it terribly difficult (I'm sure my technique isn't great, but it got the job done), so I wouldn't let a lack of soldering experience stop you from trying this.
Step 1: Materials & Tools
These are the materials I used and approximate prices (for several items the smallest quantity you can buy it in is much more than you will need for this project, so while it would be somewhat expensive if you were buying everything from scratch, the actual cost of the materials used is fairly reasonable):
- Wooden Box $10.00 (The box I used is listed at $20 from Michaels but 40%-50% coupons are fairly easy to come by online).
- Chalkboard Paint $10.86
- Paint & Primer Spray Paint $3.87
- Sample sized paint for lettering $2.94
- Painter's Tape $5.87
- 4x Red LED $2.00 (4 x $0.50)
- 3x Green LED $1.50 (3 x $0.50)
- 4x 75 ohm resistors $0.49 per 20
- 3x 150 ohm resistors $0.49 per 20
- 7x Toggle Switches $3.15 (7 x $0.45)
- Velcro sticky back strips $2.93 per 12
- Sand Paper $4.67
- 3 AA battery holder $1.95
- Solder $11.99 per 6oz
- 22 AWG Stranded Hookup wire $2.79 per 25'
- Electrical tape $1.49
- Transfer paper $11.54
- Felt padding $3.28 per 3
- 3 AA batteries
- Set of briefcase latches $3.23 (Optional) & mounting screws
- Heat Shrink Tubing $3.69 per 24 piece assorted pack (Optional)
And here are the tools I used:
- 20mm Forestner bit $14.99 (you can probably get by with a 3/4" spade - more on that later)
- 5/32" drill bit
- Soldering iron
- Wire stripper/cutter
- Hot glue gun with glue stick
- Paint brush (the thinnest you can find)
- Some type of helping hands device is useful, though probably not necessary
Heat gun or hair dryer (if using heat shrink tubing)
Step 2: Base Painting
Before you get started, you'll want to give the box a good once over with the sand paper to make sure it is nice and smooth. Then wipe it down with a slightly dampened cloth or rag to remove any wood dust. The box I used has small hinges on the back, so I put little tabs of painters tape over the hinges to prevent paint from getting in there.
As with any time you use spray paint, you'll want to have a well ventilated location. I set up some newspaper on the driveway and weighed the edges down with small rocks. Shake of the paint & primer and then use overlapping horizontal lines to get the top and overlapping vertical lines to get the sides. Personally I didn't paint the bottom, but that is up to personal preference. After letting the first coat dry for a few minutes, I went back and added another two coats to get good coverage.
Step 3: Adding the Template
Since my artistic abilities would charitably be described as "poor" I created a template to lay everything out on the top of the box. Since the box I was using was around 12" x 9", I was able to use a standard 8.5" x 11" piece of paper for the template. I've a attached a pdf of the template I used if you'd like to use the same one.
Cut a piece of transfer paper just big enough to cover the top of the box and place it dark side down, then lay your template on top taking care to center it. You can use some tape to keep it from moving, but I opted for a socket wrench that had some weight to it.
You'll want to use a slightly dull pencil to trace over all of the lines on the template (remembering to get the inner edges of the B, A, R, and O). I put a dot in the center of each of the larger circles. You'll likely run into the same problem that I did - smudges from where your hand pressed down while tracing. Don't worry about this, we'll take care of it in the next step.
Step 4: Chalkboard Paint & Lettering
Before we get into more painting I want to give an important caution: Make sure you give enough time for the chalkboard paint to dry. I kept getting impatient and wanting to move onto the next step, which led to me repeatedly messing the paint up (getting wood shavings stuck in it, uneven bumps from something coming in contact with the paint, etc) and having to strip it off and try again. If you do end up messing the paint up and have to try again, a wood chisel is really good at getting the paint to peel off in long strips.
Put the painters tape just outside the edges of the large rectangle you transferred onto the box (so that the transfer line will be covered by the paint). Make sure to firmly press the edges down so the paint doesn't leak under the tape. Give the box several coats of the chalkboard paint according to the directions on the can.
Once the chalkboard paint is fully dried, you can take care of all the smudges left over from the transfer paper. You'll do that by applying another layer of the base paint. Using a pencil and firm pressure, go over the outlines of all the letters again. What you are trying to do is make a slight indentation so that you can still see the letters once we put the extra coat of paint on. Using the tip of a drill bit, make a slight indentation at the center of all the drill holes as well. Then cover the chalkboard section and give the top of the box another layer or two of the base paint until you can no longer see the smudges from the transfer paper.
Once dry, you can then use a small detail brush to paint the letters. Since I was using paint meant for walls, it formed thick drops even on a very thin paint brush. This is why I indicated that you will want to use the thinnest brush you have, otherwise you'll find it more difficult to keep the paint within the lines. Once the letters have dried it is time to get to the fun stuff!
Step 5: Drilling Holes and Placing Components
For drilling the smaller holes where the LEDs will go, you want the hole to be smaller than the LED, but big enough for the LED leads to fit through. I used a 5/32" bit, but anything of similar size will work. For the larger holes, since the switches mount in a 20mm opening, I used the 20mm forstner bit. Living in the US, finding mm sized drill bits can be a bit difficult, so I ordered one online and found it to be fairly expensive. Forstner bits are designed to drill flat bottomed holes and since we are drilling all the way through here, you don't actually need one (the only reason I went with one is that at the time it was about the same price as the other 20mm bits I could find so I figured might as well get a forstner bit). The more economical way to go is probably to just use a standard 3/4" spade bit. 20mm works out to ~.787", so it is only around 5% larger that a 3/4" hole. You can either wobble the drill bit slightly as you are making the hole or use a file to slightly enlarge the hole in order to get to 20mm.
Once you have all the holes drilled, insert the switches making sure that they all face the same way. Even using a 20mm bit, I found the switches sat rather snugly in the hole, so I didn't need to secure them at all. If yours are a bit loose, you can use a dab of glue to keep them in place.
LEDs have two different sized legs. The long leg is the positive leg, called the anode, and the short leg is the negative leg, called the cathode. When you are inserting them into the holes, you want them to all be facing the same way in order to make wiring easier. I put a little drop of hot glue on the underside of the LED and then inserted them with the long leg on the right and held them in place for a few seconds. Once all the LEDs were in, I spread the legs apart and added a little more glue on the other side of the box to secure them.
Step 6: Connecting the LEDs to the Switches
Before doing this project I had never worked with LEDs before so had no idea how to figure out what sized resistor to use. A special thanks to redditor lampar0 from /r/AskEngineers and wayneh from the allaboutcircuits.com project forum for all of their help. If you want to use different LEDs from the ones I am using, you can figure out the correct sized resistor by using this calculator. The supply voltage would be 4.5volts (3x 1.5volt batteries), and the voltage drop and desired LED current can be found in documentation for your LEDs. Since these circuits are connected in parallel, the number of LEDs connected would be 1. I actually ended up using a slightly stronger resistor than needed on the red LEDs (150 ohm instead of 125), so the green LEDs end up a little brighter if you follow my directions, but I think it still looks pretty good overall.
Connect the long leg of each LED to the appropriately sized resistor (150 ohm for red, 75 ohm for green). Then thread the other end of each resistor through one of the switch terminals hold things in place. If you are using heat shrink tubing, you don't want to wrap it around the switch terminal just yet or you wont be able to get the tubing on later. Honestly though, I found the tubing more trouble than it was worth and if I had to do this over again, I would probably just use electrical tape instead.
Once you have resistors connected to all the LEDs, go back and solder the connections (if you need help with soldering I found several useful tutorials right here on instructables). Once all the soldering is done, cut a piece of tubing to size, and thread it onto the resistor. You can now use a hair dryer or heat gun to shrink the tubing securely in place. Now wrap the other end of the resistor around the switch terminal it is closest to and solder the connection. Place another piece of tubing around the terminal and heat it into place.
Step 7: Completing the Circuits
Now it is time to complete the rest of the circuits. The battery pack I am using already came pre-wired with a red (+) wire and a black (-) wire. I soldered on another length of wire to each of these to give me some more room to work with. From here we are going to connect each of these wires to the 7 LED/switch combinations. In order to keep the wires somewhat organized, the main (+) connection is going to be secured to the top left of the box, and the main (-) connection is going to be secured to the bottom right of the box. I cut 7 pieces of wire in each color in slightly longer lengths to run from the connection points to each individual circuits. I twisted one end of the 7 red wires together and soldered them to the main (+) connection and then connected the other ends to unconnected side of each switch. Then connected the 7 black wires to the main (-) connection and connected the other ends to the short leg of each LED.
With the circuits now complete, if you install the batteries, each LED should light when you flip the individual power switches on the top side of the box. To help keep the wires from going everywhere I wrapped the main (+) and (-) junctions with electrical tape and glued them down in their respective corners of the box. I also secured each wire to the bottom section of the box with glue to keep the wires from getting caught in the hinges when the box is opened and closed. If you want to be really secure about it, you could glue down each individual wire, but I didn't go that far.
You'll notice that by the end I got really tired of using the heat shrink tubing and didn't bother to cover the connections on the other end of the switches.
Step 8: Finishing Touches
Since this is for a younger child I decided to add briefcase latches to the box to keep it from opening unintentionally (I realize this won't actually keep him from opening the box intentionally, but a parent will always be supervising him when he is playing with it). You can also just find a box that comes with a latch pre-installed and skip having to add them yourself.
Place the latches where you want them to go mark the hole locations. Then, using the smallest drill bit you have, drill pilot holes. Since the box walls were so thin, even using the smallest screws I could find at the hardware store, they would end up breaking through to the other size. To prevent having the sharp tip exposed, I picked up some adhesive felt pads and cut them down to size. I placed these on the other side of where the screws would go and let the adhesive set for a little bit before securing the latches in place with the screws.
The last step is the secure the battery pack in place. This isn't strictly necessary, but if you don't do it, it will rattle around whenever the box is moved. Since the battery pack power switch is on one side and the battery opening is on the other, I used velcro strips to secure it the box on the battery cover side. This way you can separate the battery pack from the box when you need to change the batteries.
That's it! In the last picture you can see the complete wiring inside the box for reference. I had a lot of fun making this and found it to be a good introduction to both soldering and LEDs. Hope you enjoy.