I built a small open-source tool to solve a problem I kept running into: starting a print with the wrong build plate.

This script connects to PrusaConnect and uses a camera + AprilTags on your sheets to verify the plate before printing. When a job starts, the printer pauses, the script checks the tag, and only resumes if it matches what the G-code expects.

If it doesn’t match (or you just want to ignore it), you can still resume manually on the printer or in PrusaConnect.

How it works (short version)

• Add a small AprilTag to each build plate
• Add a line in your Start G-code defining allowed plates
• Run the script. It monitors jobs and handles the check automatically. The script only connects to PrusaConnect and does not need to be able to talk to your printer.

It basically acts as a "sanity check" before printing. For me it is especially useful if I switch between PLA/PETG/TPU.

Here is a video:

Here is how the code looks on the sheet:

This what the printer will show:

In PrusaConnect the message is slightly generic:

(Unfortunately, for xBuddy boards M117 or M0 messages are not (yet?) shown in Connect.)

If you want to try it out you can find the source at my Github repository. I will add a Docker image later.

If you try it out, I’d really appreciate your feedback! I am especially interested if it works for other printers than the Core One. Also if you know any APIs or tricky I did not find please let me know!

Jan