The drop traps I have seen have a lift gate at the far end. You position the humane trap or cat carrier up against the lift gate door, open the door and the cat is to run inside. You then use a sturdy barrier to prevent her from exiting the carrier while you close it.For now, I am trying to get her into the hard-sided carrier which she likes. She is eating out of it. If I can't close the door fast enough and she gets out, she will never trust me again. I hate feeling like I am betraying her trust. I wish she would just run inside the door! I have not given up on that option, either. But I am trying the carrier for now since she seems unafraid of it.
The homemade trap is a thought, although I have never built anything before. I am looking at drop traps online, but I need to watch some videos as I am not sure how they work since they have no bottom, how you get them in a transfer cage.
I worry about her every day, all alone outside. But she is the smartest cat I have ever known.
Here is a video too