Today I am sharing a new build project that bridges the gap between woodworking and electronics. While this creation is not directly related to drones or flight controllers, it does utilize microcontrollers in an interesting way. The centerpiece of this project is a laser cut LED Teddy Bear. This piece features LEDs mounted at the back to emit light through a cutout shape made from plywood. It includes additional engraving and finishing touches to enhance the surface appearance. Since this project combines woodworking techniques with electronic design, I will divide the discussion into two main sections.
First, I will explore the challenges encountered during the creation of the wooden component. The process involved cutting out the teddy bear shape from 3mm thick plywood. This was not straightforward and required several attempts to figure out the main cause for failures before finding a working solution. The entire project can be cut out from a single A3 format plywood sheet, resulting in final dimensions of 33cm x 26cm. Second, I will focus on the electronics. The heart of this project is the Raspberry Pi Pico microcontroller, which controls the LEDs. You can control them via touch sensors placed at the back of the legs. These sensors allow for changing brightness and operation modes.
This project demonstrates how simple hardware like a single board computer can transform a crafted wooden item into an interactive piece. The combination of laser engraving techniques and programmable lighting offers a unique visual effect that is both pleasant to the eye and visually engaging. Whether you are interested in the vectorized cutting solutions for plywood or the GPIO configuration for LED control, this post covers the essential steps taken to bring this project to life.
Woodworking and Laser Cutting Challenges
The first part of the build focuses on the physical creation of the teddy bear using a laser cutter. I started with an image of the Teddy Bear and decided to cut it out of 3mm thick plywood. To reflect different shades of gray, such as the cheeks and shadows, I created layers of different colors which directly transferred to the power of the laser. This allowed me to control how much the laser burned the image on the plywood.
I needed to divide the process into several parts because cutting out is just cutting out of the shape in the plywood, but engraving requires precise control. Initially, I attempted to use the capabilities of the control software which is capable of printing out images directly on the plywood. However, this method resulted in stretching only in a single direction, length-wise. This caused overlap issues when the cut-out part did not correspond to actual dimensions due to imprecise step motor control.
Description: An image showing the gap issue encountered during initial laser engraving attempts.
To solve this, I decided on a safer option meaning that I created separate color layers and then used a vectorized way of controlling the laser cutter in order to cut out the shape and put the engravings. After applying those different color layers, I had the internal part of the teddy bear, and finally, I was able to cut it out perfectly. Additionally, I used a single layer of glossy clear varnish on the surface to enhance the colors without sanding. This single layer was enough to bring out the colors, and I really liked the end result.
Description: A cut-out teddy bear covered with a single layer of glossy clear varnish
Electronics and Microcontroller Integration
The second part focuses on the electronics. As you can see at the back, all the components and wiring are placed behind the wooden shape. There are a few main components which include the Raspberry Pi Pico. The first edition of the Raspberry Pi Pico is more than enough to control everything. A bunch of programmable LEDs WS2812 are controlled through PIO, a special feature of Raspberry Pi Pico microcontrollers.
Description: A view of the back with the Raspberry Pi Pico and LEDs attached to the plywood.
The LEDs are connected in a shape of LED tape glued at the brim of the back. Additionally, two touch sensors are placed at the back of the legs of the teddy bear which allow you to control the brightness and modes. The wiring may not be done perfectly, but it works. There is a bus of positive plus 5 voltage as well as ground. The bus was made of a thin copper sheet. I have tried it for the first time and it works and looks quite nice. The wires are soldered to the bus and then connected to the components. The application is straightforward because it only reads two digital inputs for those two touch sensors, so you can touch the legs of the teddy bear, and then appropriate action will be carried out through the software.
Description: A view of the back components including wiring and sensors attached to the plywood.
The most challenging part was how to glue or shape the LED tape. The tape itself has a copper backing which is quite hard to shape. I needed to bend it really hard in order to provide the actual shape so the LED stripe followed the brim of the shape. How everything is connected together can be seen in the video below.
Description: A schematic or photo of the wiring connections between the Pico and LEDs.
Features and Modes of Operation
About the capabilities of the teddy bear, there are 5 modes of operation. There is warm light which is pleasant to the eye. There is cool light or really bright light. The third mode is chasing LED which is a bunch of LEDs running around in a circle around the brim of the shape. The next mode of operation is heartbeat using warm light. It is also a really nice little bit of calming so it does good. Finally, the fifth mode of operation is random colors. With this random colors are randomly drawn and the color change is smooth between them.
Additionally, you can confirm the brightness with four levels: low, medium, high, and maximum brightness. You can also turn it off immediately so you do not need to cycle through all the modes. As for the wiring, there are actually three, or you can say four GPIOs used. There are two buttons connected to the touch sensors, one for changing the mode, one for changing the brightness. One GPIO output confronts the WS2812 programmable LEDs. Through PIO, in total there are 75 pixels and this matters because if there is more or less LEDs, then one of the modes will not work properly (chasing LED). The fourth pin is the analog input. It is used to initialize the random number generator. The seed for the random number generator is used to provide some random looking initial values for the random color mode of operation.
Resources and Downloads
Finally, for all of my readers I provided two things to download. You can download the cut out shape as SVG, so vectorized form of the cut-outer shape of the teddy bear. Additionally, there is a combined version of the firmware for Raspberry Pico, UF2 file, pre-configured for those 75 pixels of LEDs.
For my supporters, I offered the entire project which includes:
- Project for laser cutting and engraving, including the SVG shape of the cut-out and colored layers.
- If someone would wish to engrave it as an image the entire picture of that teddy bear is also available for download.
- Full source code for Raspberry Pi Pico so you can look into the code, adjust the number of pixels or LEDs, maybe change the modes, add something new or remove them.
Some content is only available for the people who support me. If you would like to access that content consider buying me a coffee ☕. Thank you!
LED_Teddy_Bear_software.zip
teddy_bear_edges_full_laser_files.zip
Thank you for supporting me. I always try to repay with some additional materials as you can see.
Conclusions
In summary, this blog post details the creation of a Laser Cut LED Teddy Bear that integrates traditional woodworking with modern electronics. The project begins with the physical construction of the bear using 3mm plywood cut from an A3 sheet. Significant challenges were faced regarding laser engraving precision and image stretching, which were resolved by utilizing color layers and vectorized cutting methods rather than direct image printing. A glossy clear varnish was applied to enhance the surface colors effectively.
The electronic component is driven by a Raspberry Pi Pico microcontroller, specifically configured with PIO for 75 WS2812 LEDs. Touch sensors located on the legs allow users to interact with the device, adjusting brightness and cycling through five distinct modes of operation: warm light, cool light, chasing LEDs, calming heartbeat, and random colors. The firmware includes a seed for the random number generator to ensure varied color sequences.