Its a mousetrap derived from the venus fly trap. The principle is simple: Mouse steps on a plate, mouse falls down in the chamber, the trap closes above the mouse, thus trapping the mouse inside.
The picture is from a facebook game called mousehunt. For added realism, add something that can dissolve mice

Print the 3 pieces. They should not be bigger than 8x8x8cm in size. Use some glue and paper, or elastic bands, to make sure that the trap stays on top. A typical mouse weighs around 10-25g, so make sure that the paper rips as soon as the mouse steps on the plates. I would recommend eating paper. Put some smelly cheese in the middle and the rest should explain itself.