[Paul McCabe] wrote in to let us know about his $25 robot. This small wheeled robot is based on an ESP32 and made using cardboard and hot glue.
You drive the contraption using a Bluetooth game controller thanks to the Bluepad32 library, which boasts a long list of supported hardware. [Paul] provides a Bill of Materials (BoM), complete with current component pricing. We don’t know about you, but it struck us as funny that the microcontroller is less expensive than the battery! Ah, the times we live in. Also [Paul] assumes you already have an appropriate Bluetooth controller and doesn’t include that in the total cost.
The software and related material is available on GitHub: github.com/paulemccabe1/DirtCheapRobot. The Arduino-flavored source code is here: DirtCheapRobot_Code.ino.
At time of writing [Paul]’s next steps are listed as:
- Investigate ESP32 boards with built in LiPo charging so a smaller LiPo battery with a JST connector can be used
- Eliminate use of the breadboard
- Create Soccer Robot with linear actuator for kicking
We wish [Paul] every success. If you’re interested in cheap robots you might be interested in a cheap robotic mower or a cheap robotic microscope.

To me, the term ‘robot’ implies autonomous behavior.
Just glancing at this, it seems more like a remote control vehicle.
I was thinking the same. Cool, thought.
*though
I was thinking the same. Cool though.
If it can do a “hard work” it is a “robot”. Does not matter if it is autonomous or not. The equipment use to film the Titanic are called underwater robots, but they are not autonomous, the are guided by an operator.
In automobile factories, the robots are preprogramed, but not autonomous.
So, the question is: what is a robot?
Oxford languages:
1. a machine capable of carrying out a complex series of actions automatically, especially one programmable by a computer.
It’s simple, and cheap. I love it. I’d love to see more 2 motor robots
I’m surprised this great use for unused Android cell phones isn’t more popular:
OpenBot: Turning Smartphones into Robots (2022)
https://www.youtube.com/watch?v=RbzPXywJifA
Last update in repository was 8 months ago, so it’s still active:
Turning Smartphones into Robots
OpenBot leverages smartphones as brains for low-cost robots. We have designed a small electric vehicle that costs about $50 and serves as a robot body. Our software stack for Android smartphones supports advanced robotics workloads such as person following and real-time autonomous navigation.
https://github.com/ob-f/OpenBot
Hot glue and cardboard is exactly my level of ability — projects like this give me hope. And I did not know about the DRV8833 (https://lastminuteengineers.com/drv8833-arduino-tutorial/)…very cool!
Pleased to hear it! If you get inspired and make something fun be sure to write it up and then get in touch to let us know!