Turkey traps are man made on site mostly. Although you can purchase some forms of turkey traps from outdoor and hunting type stores, the man made ditch, logs and corn method has been working just fine for trappers, and hunters for hundreds of years. Building a turkey trap is fairly easy and cheap to construct. The actual structure that holds the birds is made of logs, sticks, large branches, pretty much what ever you can find on the floor of the woods or laying around the yard.
The turkey trap should look something like a box made of logs. The most laboring part is the actual ditch digging. The cage structure is built somewhere in the center and on top of the ditch. It must be covered and the logs should be tight enough together that the birds can not escape but they can still get air and light in the box. After all the construction is complete corn gets thrown around and in the ditch leading into the cage or pen that will hold the birds.
No bottom should be necessary for the turkey trap and it will not drop down and catch the bird once inside because the fact is turkeys are just not smart enough to duck down and escape the same way they came. As long as the ditch is not so long that they can see the light well from the bottom of the trap coming in the pen they will just walk in circles until they get pulled out by the trappers hands. Adding a pile of corn in the trap will keep the birds calm and stop them from panicking after all that is what they were after when they walked down into the ditch and up into the pen and got trapped.