If you would like to create your own qrcode, I have discovered a very useful tool for Linux. It’s called qrencode. The syntax is very simple:
echo YourMessage | qrencode -t UTF8
And if you want to keep your message as a file :
echo YourMessage | qrencode -t png -o YourFile.png
We can also play with the error correction with the -l option to make sure that our qrcode is still readable even on a wrinkled T-shirt:
echo YourMessage | qrencode -t png -o YourFile.png -l H
The error correction can be set to L,M,Q or H in ascending order.