This guy did just that:

https://youtu.be/qy_9w_c2ub0

Thought it was a really cool idea / project. Essentially a modified Z Flip.

This was an interesting video / project I quite enjoyed.

https://youtu.be/qy_9w_c2ub0

Watched a guy using an air horn on his bike riding around a European city using it on people walking in the bike lanes. So many people had no idea they were in a dedicated bike lane. Either blocking it or walking in it or crossing over it right in front of him.