I used to trap rabbits as a youngster in box traps; I'll try to describe one.
Make a four sided box about 6" on a side and 24" or so long. Close one end with hardware cloth. Make a treadle form a piece of word about 8" long about 1/4" too ½ narrower than the opening. Do the same for the door but make the door about 1/4" longer than the opening. You can bevel the bottom edge of the door such that it closes neater, but so it cannot swing outward, even if kicked from the inside.
Drill holes on each side of the box near the top and front opening for nails to be inserted and driven into the top of the door for hinges. Drill a hole on each side of the box about 1" from the bottom and 6" from the end which you will cover with mesh. These holes will hold the nails that you drive into the middle of your treadle board and act as the fulcrum for the treadle.
The trigger is made from a coat hanger. It is attached to the front corner of the treadle. This can be done in a number of ways: drill a deep hole and insert the wire into the treadle or attach it to the bottom with a number of small fencing staples; remember it must rotate freely. Using two or three more staples, form a line of guides along one side of the box from the front of the treadle angling back to near the top of the side and near the bottom of the door when it is up in the open position.
When the bunny enters to get the apples or apple sauce, which is in the space between the front of the treadle and the meshed end, it moves onto the treadle causing it to fall forward which in turn pulls the wire from under the opened door. The door falls and you got a rabbit.
Assemble the trigger side with all holes, trigger wire door and treadle and make adjustments first. Also, nail a cross strip in the floor just in front of the treadle to keep bait from getting under the front edge of the treadle.
One last modification is to drill a hole through the top on the center line just behind the closed door. When the trap is set put a nail in this hole. Once triggered, the door closes; the nail drops and the door cannot open until you lift the nail out of the way.
Hope this helps some.
