We need claw machine for chat to play on their own. A claw machine and a 3D printer are fundamentally the same kind of machine… Both move on an XY axis, and with a Z axis that has an extra function. So buying an old used machine for cheap is the perfect head start on this build.

I acquired a Creality Sermoon D1, which is fully enclosed. It’s not required for your printer to be fully enclosed - you will print walls up around your print bed to hold the prizes - but it’s an advantage as far as keeping stray balls from flying out or keeping a curious cat out of it while it’s moving.

The Claw

The claw is printed from TPU with three fingers. A single servo pulls strings to close the fingers and releases them to open. The bed moves up toward the claw rather than the claw descending, but the end result is the same. The design was remixed from a 4 finger version.

See the 3d files in my github repo, or here:

https://www.thingiverse.com/thing:7351307

Control

An ESP32-C6 handles Wi-Fi and hosts a web UI. It connects to the 3D printer motherboard over serial and sends G-code to control movement. It also connects to Twitch chat and listens for commands. When a trigger is received, it moves to the target coordinates, closes the claw, returns to home, and releases.

Cameras

A Raspberry Pi Zero streams two cameras over RTSP. A standard webcam mounted above gives a top-down view of the whole bed. For a POV shot, I used a cheap USB endoscope camera. Endoscopes meant for phones over USB show up as plain USB webcams on Linux and Windows with no drivers or apps needed. They are ideal here because they have a short focal length, wide angle, and are small enough to fit in tight spaces. Adding a POV camera really adds to the immersion of operating this remotely.

Use ‘ustreamer’ on your raspberry pi and it can stream usb webcams with way less CPU usage than other programs.

Power

The original 3D printer ran on 24V, so I powered both the Raspberry Pi and ESP32-C6 using a car USB adapter. Many 12V car adapters also accept 24V input, so no separate supply was needed. You will want to make sure your 5v supply is robust… better if it outputs above 5.2V… if the supply sags too low, the raspberry pi is likely to have reliability problems especially with 5v powered usb devices (the cameras).

Prizes

I fill the bed with small toys and plastic prize balls. Inside the balls I put M&Ms, or cat treats for some of them. If someone in Twitch chat grabs one, I eat it (only the M&Ms of course) or give it to my cat. So far I have only accidentally thrown one cat treat into my mouth before realizing and spitting it out.

Because I have to keep a bulk jar of M&Ms, I also had to develop a lock for it so I can’t eat it off stream. See that here: https://daverdavid.com/proj/candylock/

Resources

All code and 3D printing files are available on the github: https://github.com/DaverDavids/CrealityClaw

Thingiverse remix: https://www.thingiverse.com/thing:7351307