Backwoods Presbyterian
Puritanboard Amanuensis
I found some videos on making door hangers.
That's doing it the hard way. Take your printed card, use a hole punch to put a single hole in the top middle, thread a rubber band through the hole and through itself, and hang the rubber band over the knob. If your card is printed on one side, you can write a brief note on the other.
Those 1 1/2" hole punchers are only $10 at Walmart and skips having to buy rubber bands.