Angie4444

You're not leaving stuff constantly, just a time or two through out the cruise. However, if you have 5-10 families participating then you could end up with a few cool and exciting things to brighten your trip.  Logically you would be by your door at least 3 times (leave, come to freshen up before dinner, and return for bed)   Think if you came back to freshen up and someone from Ohio like myself left you a few homemade buckeye treats for you to enjoy, or in the morning before your first shore excursion someone made you a personalized water bottle or left a mini care package with hand sanitizers, Band-Aids, and  a pack of advil, or maybe when you return at the end of the night someone left you a few breath mints. ;)
 
Even without kids I would want to participate.  :)  it can be an icebreaker and a way to meet an remember new people.

CC roll calls are hit or miss.  For my Liberty cruise this coming January (88 days to go), we're only up to the second page.  For my Serenade cruise next July (Northern Europe), we've just hit 22 pages.

I noticed they have a decent roll call and forum on my Shipmates app, may be worth a look. I would expect CC would be the largest though.

I hope you can find some folks to try this out with!

I've never seen this on any other line. My advice would be to join a roll call thread on a site like Cruise Critic to see if others are interested in doing something like this.
 
We did a hometown gift exchange once at a Meet and Mingle, but that's the closest thing I've seen to the fish extenders. You also won't see many decorated doors.