I created this Airstream handset lock plug in Tinkercad. It fits perfectly in the slide lock opening of our Airstream Flying Cloud 27FB. The design would have to be mirrored to fit a rear bed Airstream, I believe. I print these in TPU so they're flexible enough to get the back stop, which prevents it from falling out, in place. I printed in black so it blends in with the door but a different color would allow you to more easily see at a glance if the plug is still in place.