4x4 LED Cube for Raspberry Pi Pico

This 4x4 LED Cube will give a great introduction to more complex circuitry as well as providing more than a little experience soldering.

Here are the list of supplies. If I bought anything I have included the link to it as well for reference.

Purchasable Materials:

1. 64 x 5mm blue led
2. 1 x Brass Wire Spool
3. 4 x 100e Resistor
4. 1 x Raspberry Pi Pico
5. 1 x Breadboard
6. 1 x Set of headers for Pico
7. 1 x Soldering Station

You will also most likely need access to a 3d printing station of some form for a container print.

An LED Cube is something where any disruption to symmetry is going to be incredibly visible to it is going to be important that we start with a way to guarantee each layer looks the same as the last. The first step is going to be one of the more important ones for the uniformity of the build and that is a base to assist in the lights layout. Personally, I used a laser cutter for this but realistically you could do the exact same thing with as little as a drill and a piece of wood.

Steps:

1. Cut a 4x4 piece of wood (any thickness but thinner is best)
2. Start 1/2 inches from the top and 1/2 inches from the left and mark a hole
3. Mark another hole 1 inch away from the first
4. Repeat two more times
5. Make three rows below this all spaced out 1 inch from the one above it
6. If you are drilling then on the marked points use a 5mm drill bit to drill the holes
7. If you are laser cutting then etch out a 5mm hole with the software of your choice and cut
8. Once the holes are drilled start from the leftmost column and mark - + under the hole (- on the left and + on the right)
9. Repeat the same for the second column
10. For the third and fourth column reverse the order (putting + on the left and - on the right)
11. Draw a horizontal line through the center of each row of holes

At the end you should have a grid of 16 holes each spaced out an inch from any neighboring hole. This is going to be used as your blueprint for creating each layer of lights.

Another important aesthetic step is in making sure that your brass wire is straight. It is also important that it is structurally sound and allows the cube to stand without wiggling. Thankfully, both of these issues are solved by a drill without a drill bit.

Steps:

1. Cut 44 pieces of brass wire (around 5 inches each)
2. Curl a small part of one end back towards itself (see right side of the wire in the first picture for a more visual explanation)
3. Place the curled part of the wire into the socket of a drill and tighten until it is securely held
4. With some pliers, hold the end of the wire and slowly turn the drill. This should make a nice and straight wire as shown in the third picture
5. (Optional but recommended) Find some music or a podcast and turn it on because this may take a second
6. Repeat this with every piece of wire

At the end you should have a nice tidy pile of rod straight wires perfect for the structure and look of your cube.

For this step we are going to start warming up the soldering skills and making the horizontal layers of lights used in the cube. We start with the rows, then connect them all with a single wire on each side.

Steps:

1. Take an LED and separate the legs so that they are at a 90º angle from the light
2. Using the handy wood template we made in Step 1 place the positive end on the + side and the negative end on the - side (picture 1)
3. Place a vertical line of lights and place a single brass wire under the positive end of the LEDs (picture 2)
4. At each of the connections solder the positive end of the LED to the brass wire
5. Repeat this for each of the rows making sure to swap the side of positive and negative for the third and fourth columns
6. After each is soldered, place a brass wire at the top and bottom and solder the points where it connects to the other brass wire (picture 3 for more of an explanation)
7. Repeat this 3 more times

At the end you should have 4 individual layers of lights primed and ready for connection.

This step is going to be focused more on 3D printing for the base and container that will eventually house the light. For this step you need to do nothing more than download the provided files and print them on your 3D printer of choice. After these pieces are printing, you will prepare the lights_base for soldering.

Steps:

1. Taking the lights_base piece we are going to create a 4x4 1-inch grid starting at 1/8 inch from the left and 1/8 inch from the top
2. This should be slightly offset so that the holes are not directly underneath the led lights
3. Once the grid is drawn, take a 1/16 drill bit and drill holes through the lid at the connection point (picture 2)
4. When all holes are drilled, feed a piece of brass wire through each of the holes (picture 3)
5. Flipping the base over, bend the end of the wires so that there is a small amount holding it in (picture 4)

This step will bring the cube to its full form and allow you to finally test the LEDs.

Steps:

1. Slide the first layer onto the base lining up the vertical wire with the negative end of the LEDs (picture 1)
2. For each LED, solder the negative part of the LED to the brass wire (picture 2)
3. When the entire layer is done, find an object which is 1-inch tall (for me this was a random scrap piece of wood) and place it on top of the layer
4. Slide the next layer on top until it touches your spacer (picture 3)
5. Remember to remove this spacer from the cube BEFORE the layer is fully soldered
6. Solder this layer and repeat the whole process for the last two layers
7. Once the layers are done, create 4 brass wires with a small 90º turn at the end. Place them on a side of each layer and solder them on (picture 5)

You should now have a full LED cube. Congrats! You can now take your breadboard and test the lights individually using alligator clips (picture 4). I took a while to check them all and play with the powering of whole rows at a time and would recommend you do the same as I had some issues with lights getting burned out in the soldering process

This is one of the final steps of the project but also one of the messier ones. It is the point where we connect all of the wires to the pins which are bent through the bottom of the base

Steps:

1. Number the bottom with a matrix

1. Number the vertical pins placed in the last part of step 5

1. Strip and solder the ends of wires to each of the brass pins (as shown in the pictures)
2. Once a wire is connected to the brass pin, solder them to the pin GP__ which matches the number sharpied on the base of the box
3. Repeat this process with every one of the wires
4. Be sure to keep the wires on the same row together as this will make packing them easier and organization simpler

For this step it is up to the user. If you are using the box that I am (provided a few steps ago) then this step is fairly straightforward. All you have to do is to cut a hole in the side the size of the CPB and provide space for the charger. Then, place hot glue on the side and solidify the connection of the board to the box. After this is done you are able to place a little glue on the top and close it off. Then you are done. Congrats!!

This is the code that I used. It is incredibly easy to make your own animations. All you do is treat the lights like an indexable 3D matrix and everything is callable by nothing more than indexing lists.