Introduction: Interactive Climbing Wall

Through this tutorial you will learn how to make the components to build an interactive climbing wall. You will use castable resin, basic LED circuitry and a Bluetooth microcontroller device to enable your phone to dictate the level of difficulty you wish to climb on the wall.

Be aware that this is a big project that will require lots time and resources. You might want to start by exploring one of the techniques covered, like how to create a climbing hold.

This list covers pretty much everything you will need if you wish to follow the entire project through.


- Plasteline (sulphur free, also called “clean clay”)

- Mann Ease Release 200 - Mold Release spray

- Scrap Postcards - Shinny/smooth finish or styrene sheet

- Hot glue

- Mold Star 30, Silicone Rubber for molds

- Clear Urethane Resin - Smooth-on 326

- A sheet of 3/4” plywood

- Neo-pixel strip - 26 lights total

- Adafruit Feather 32u4 Bluefruit LE

- 3 Pin JST connectors

- Solid core cable - three colors

- Solder

- Heat Shrink Tubes


- 3/8” - 16 Socket head bolts

- 3/8” - 16 “T” Nuts

- 3/8” washers


- Hot Glue Gun

- Clay Carving tools

- A few 1-quart mixing buckets

- Drill Gun Drill bits

- 5/16 Allen key

- Wire Cutters

- Wire Strippers

- Soldering Iron

- Multimeter

- Heat Gun

Step 1: Carving the Holds, Molding and Casting

This is probably the most fun part of this project, designing custom climbing holds that you can cast yourself. Please be advised that this is a prototype. The urethane resin used here has not been tested in an actual climbing environment, and I can not vouch for their safety!

Step 1A: Sculpting the holds

Start to sculpt your holds by warming up the Plasteline in your hands and exploring the forms you like. If you have climbed before, you will probably know what kinds of holds you like, look at examples and decide on a few different kinds. For some of the examples on my wall I tried to design the holds so they can be used in different orientations, that way I get more variety overall. As you sculpt the clay be sure to keep the back of the piece as flat as possible. Once you have a rough shape you will want to use the 3/8”-16 bolt and the washer to carve out the hole. This is where the clay carving tools will become useful, they will help you clean up the inside of the hole and flatten the back. You should also use your carving tools to carve a void big enough to encase an LED light.

Once you are happy with your form and the surface is smooth, you will want to add a texture. Be creative! anything that you can press into the clay to create texture will be good. I used a wire brush, and the result was really nice. You could also use a rock, for example.

Step 1B: Making a 2-part Silicone Mold

Now it’s time to prepare and build your mold. First you will want to build the wall of your mold (see in the pictures for reference) you can use postcard type material, as long as it is somewhat rigid and has a shinny non absorbent surface. I used scrap styrene sheet I found in the shop. Place your clay hold on a flat piece of styrene and outline around it with a sharpie, 1/2-3/4” around should be plenty of space. Remove the hold and use hot glue to secure the wall down all around, make sure it is completely sealed, you wouldn’t want your expensive silicone to start leaking out of the mold! believe me, it is not fun!

Now place your hold in the center, and add a cone of clay which will become a your pouring channel, be strategic with the placement. You will also want to add 2-3 small cones around your shape, these will be your mold keys, they will help your mold align correctly every time you pour a new hold (see pictures).

Now its time to pour the silicone. Before you do this spray Mold Release on all the surfaces inside your mold, let it dry for 5 minutes. SAFETY! At this point you should be in a well vented area, you should wear a respirator to protect you from the fumes, and be wearing long sleeves and gloves. Mold Star 30, like most molding compounds, comes in 2 parts, in this case you will want equal parts by volume. Use a 1-quart mixing bucket to measure, then mix the contents thoroughly for a few minutes. You will be ready to pour into the mold once the mixture has no streaks showing (read the instructions from smooth-on, they really informative). When pouring the silicone be sure you have about a half inch over the highest part of your hold, this will ensure a good mold. Let the mold sit still for 6 hours.

Now, ready for the second part of the mold. Use a knife to cut the bottom piece of styrene. Keep the side wall together. Clean any silicone that might have seepped under your form (see pictures). Now Push the mold down about 3/4”, spray mold release, let it dry for 5 minutes. Mix and pour another batch of silicone, let it set for 6 more hours.

Now you can remove the clay positive and you are ready for the next step.

Step 1C: Casting in Resin

To prepare your mold for casting positives of your holds in Resin start by making two caps for your it in a thin stiff material like 1/4” plywood or mdf. This will help keep the mold together with rubber bands without deforming it. Spray mold release and let it dry for 5 minutes.

For my holds I had access to a vacuum chamber which helps minimize bubbles, this is not required, but a nice thing to have access to. Similarly to the Silicone, the Smooth-cast 326 Resin is a two part mixture equal in volume. Mix thoroughly and pour into the mold. Let it sit overnight before de-molding.

Step 1D: Cleaning up the resin cast

After de-molding the resin you will want to saw off the pouring channel, file and sand that area smooth as well as the back of the hold. If you have access to a belt sander this will be really quick, just be really careful, specially with smaller parts. Otherwise, just tape a piece of sandpaper onto a flat surface and flat sand the back of your piece.

Step 2: Laying Out and Soldering the Circuit

First thing you will want to do is figure out where on your wall you want you holds. Use paper cut-outs to outline your layout and then tape the pieces of the circuit in order, right on the layout ‒as you see on the first picture‒ this will help you keep an order and keep your sanity as the project progresses. Number your holds in order, some holds have 1 LED, some have 2, so make sure your numbering reflects that, this will be important information to have for the programing phase. Take pictures of your final layout, it will be a good reference.

The circuit is pretty straight forward, 21 NeoPixels arranged in a chain, separated by long wires to reach from one hold to the next. Note that when longer bits of wire are soldered like this, the circuit might experience lag, the way to fix this is to add more power and ground cables along the way. Start by adding them to the end of your circuit and see if it all lights up consistently. For my project I ended up adding 4 more ground and power cables. The middle cable in the NeoPixels labeled DIV is the one that carries the programing to the NeoPixels, this you will want to leave as is.

I used a JST connector every 3 or 4 NeoPixels so that errors in the circuit can be easily fixed.

Before you start putting the NeoPixels in the wall, you will want to start drilling holes to secure the holds. See next step.

Step 3: Securing the Holds to the Wall

To secure the holds onto the wall you will want to become familiar on how to mount T-nuts onto the wall, this video from Three Ball Climbing explains the correct way to do so. Once the T-nuts are in, drill a second 7/16" hole near every T-nut so that it lines up with the hollow part of each hold, this will be the placement for your LEDs. Fedd the LEDs into each whole in order. Once al the LEDs are in, you just need to screw the holds in using the 3/8"-16 screws, a washer and the allen wrench. Tighten as much as possible by hand, as you want to avoid having the holds spin.

Step 4: Programming the Wall

To program the wall I used the Bluefruit LE Module from Adafruit that I mentioned before. In the picture you can see how it is all connected. You will notice the additional ground and power cables.

Once it is all connected you will want to first test the connection to the Bluetooth Module following the instructions on the Adafruit website. The code attached is specific to my arrangement, which uses 21 NeoPixels total, but it should be pretty easy to modify.

In this area you can program the 3 different routes:

<p>//LED Combinations<br>    int easy[] = {0, 1, 2, 3, 7, 5, 6, 9, 10, 8, 13, 14, 15, 16, 17, 18, 19};
    int easyLength = 17;
    int med[] = {0, 1, 2, 3, 4,  9, 10, 8, 11, 13, 14, 12, 17, 20};
    int medLength = 14;
    int hard[] = {0, 1, 2, 3, 4, 7, 8, 11, 12, 17, 20};
    int hardLength = 11;</p>

Later in the code you will call these under animationState which corresponds to the buttons in the BlueFruit LE App

<p>if (animationState == 1){ // button labeled "1" in control pad<br>   easyAnimation();
  if (animationState == 2){ // button labeled "2" in control pad
  }</p><p>  if (animationState == 3){ // button labeled "3" in control pad

To animate the color changes this is the code I came up with to Jenna W. my classmate, who is a code wiz:

// easy route starts here
void easyAnimation(){
uint16_t i, j, n; int green = 250; int blue = 0; if (newCommand){ // Clear Pixels colorWipe(pixel.Color(0,0,0), 20);

//Initiate Lights for(i=0; i

if (blue == 250){ bluestate = 0; } } else if(bluestate == 0) { green = green + 5; blue = blue - 5; for(n=0; n

if (blue == 0){ bluestate = 1; } } delay(100);

} }

These are some of the projects on the Adafruit website that I used as reference:

NeoPixel Ring Bangle Bracelet

NeoPixel Citi Bike Helmet

Once you get through the coding you will almost be ready to climb! To mount V+ to the wall I had to build a frame out of 2x4s, which you will need to get the plywood piece off the wall, so the cables and nuts have a space to live.

DISCLAIMER: to install this project on a wall you will need to use proper anchors. To do so safely be sure to do the research about the material of your wall and an anchoring mechanism with the highest rating!

If you have gotten this far, it means you might have built this and I wish to see the results of your climbing wall! so please share your experiences below. I would also be curious to know what other people do with the code, so please comment below. Looking forward to your projects!