Using a basket and twig, you can make a small trap. When you bring up the sub menu and tap "backpack," start to hit the A button until the backpack menu pops up. Just before it pops up, the character will be bent down to search the ground.

Next you tap the trap and a little menu will pop up. Tap "use" and the trap will disappear from the backpack menu. Exit the backpack menu, and the character will pick up the trap.

Leave that area and come back later, and a trap will be there. Do this as much as you want, but be careful not to place too many. If you have too many traps, the dupe will not work, and you will lose your trap.