We just built what we called "box traps" when we were kids. Scrap wood box approximately 5"wide x 6" or so high and 15" or so long. A drop down door trigged by a notched stick in the rear of the box dropped the door.
I am sure an example can be found online somewhere.
That’s all we ever used when I was a kid, caught a bunch. Can’t remember ever catching a possum.
