High-rise beds are cool and all, but when you have to climb all the way down to answer your door, you might start to wish you’d chosen function over fashion. That was a daily dilemma for maker Varun Patel, until he built an RP2040-powered to device to open the door for him.

You might know Varun as Blue Hand Coding. He posts tons of videos showcasing his “over-engineered solutions to nonexistent problems”.

Hardware

• Arduino Nano RP2040 Connect (built on our RP2040 chip)
• Motor
• Motor driver
• Adhesive strips to stick it to the door
• 3D-printed parts

Door-opening device design

Version one of the door-opening device, which was mounted above the door handle and designed to push downwards on it, didn’t work at all, so Varun flipped the design for version two. This device is on the inside of the door and uses a motor to push up a 3D-printed arm which connects with the underside of the door handle and lifts it. He also designed a third version in case v2 didn’t work, but that was a little too beefy. Watch this TikTok running through the design of all three iterations. Varun wrote all the code and did the CAD for the 3D-printed parts himself.

The device pairs with an app which sends the signal over Bluetooth to the Arduino Nano RP2040 Connect that Varun wants to open the door. The motor is then kicked into gear and starts rotating the arm up to meet the door handle and unlock it.

Is this safe for your setting?

This creation doesn’t just work for guests, but also for Varun himself when he forgets his key. You need to think carefully about whether building something like this would work for your home setting. I like that the door doesn’t even look like it’s unlocked from the outside; the position of the exterior handle doesn’t change, so you have to know to listen for the motor and to push on the door when you hear it has stopped running. Varun’s system also means he has to be the one to ask the door to open on the app, and I imagine he also messages expected guests asking them to let him know when they’re at his door. Or maybe Varun also devised a special knock as a tech-free element to the project. That would be cute.

Stay tuned to Varun’s various channels to follow his journey to automate his dorm room.