When we lived in Washington my kids and I would make taps for St. Patty's Day. Here are some pictures of some of them and what we did to try to catch one.
This trap was by far the easiest! It was made out of an empty tissue box. It was already green and St. Patty's Day-ish. All we had to do was add a shamrock with a little note on it for the leprechaun and sprinkle some "Lucky Charms" around. We didn't catch one, he just left some of his loose change behind and some black foot prints to a rainbow trail which led to some yummy treats.
This trap was my favorite. It is made from an empty oats container, some green, black and yellow paper and some green saran wrap. Also, it wouldn't be a leprechaun trap without "Lucky Charms".
Lastly, this was the first trap we made. This trap is from an empty tissue box. This is the one the kids were able to have fun with. We wrapped it in green paper and the kids decorated the box. We propped it up with a plastic spoon and left some bait.
Here are just a few ideas to have fun with the kids and try to get ya some of that leprechaun gold.