This is an inexpensive, firm-density polystyrene board (like hard, closed-cell styrofoam) that is designed for spreading insect wings prior to mounting. It is ideal for allowing butterfly wings to spread and dry. The spreading board has a body slot that is 3/8" deep and varies from 1/4" to 1/2" wide, depending on our supply.
Place a moth, butterfly, or other insect's body in the indentation on the spreading board, and pin a thin strip of paper over each wing to hold them flat until they dry out.