I never have personally but I know a lot of people who have. First time I ever heard of these were some friends in Texas using them. Definitely always fun to walk fence lines and what not to see if they dropped them when they landed, but a rack trap is your best bet for sure.
There are all kinds of different variations in design. If you make a box, just make sure it is really tight. The idea is not for bucks to be able to get their head in there and get stuck or be walking around with it hanging around their neck. Instead, the goal is to make it tight enough where they will put pressure on their antlers trying to reach the pile of feed.
Another design is just to stick 3 poles in the ground at an angle in the shape of a triangle and put some kind of top on it.
This is one of the best designs I've seen:
http://i.ytimg.com/vi/TNBkaEXQ0D0/0.jpg . It is pretty close to that rack trap wizard posted above.