REMOVE BEFORE FLIGHT
This is a REMOVE BEFORE FLIGHT tag used to lock certain functions on a plane while they are under maintenance. This could also be used as a keychain or as a safety plug in your RC model.
I added two versions of my design. The text on one of them is going all the way through the tag, the second one has the text engraved on both sides. I strongly suggest you print this in red ABS and add a metal keychain ring on it. If the engraved model is used, I suggest you put white acrylic paint inside each letter.