Cut a piece of muslin the same size as the front and sides of a large, lidded cardboard box.
Cut out panels from the front and sides of the box. Leave a margin of at least two inches from the edges of the box around each of the three panels.
Attach the muslin firmly into position on the outside of the box with duct tape.
Place a twig in the box as a perch for the butterflies.
Mix one part cane sugar with four parts water in a pan. Warm the mixture on your stove and stir until all the sugar has dissolved.
Cut a piece of unused kitchen sponge and soak it in the sugar solution. Put the sponge on a saucer and place the saucer in the box. You now have a simple cage with all the basics for a butterfly.