Wash all clothing items that you will use for the costume, including leggings, bodysuits and leg warmers. Let the clothes dry.
Paint over leggings and bodysuits with acrylic fabric paint to add stripes, spots and other details. Look at images of cats and Cats costumes for inspiration.
Sew or hot-glue faux fur fabric onto each pair of leg warmers. Wear the fur-covered legwarmers over the leggings. Use leftover fur fabric to make simple mittens, gloves or wrist cuffs for added wearable fur.
Paint over colorful wigs using the same acrylic paint you used on the leggings. Add stripes, spots and other details to the wigs so that each wig corresponds with a pair of leggings and a bodysuit.
Cut cat ear shapes out of leftover fur fabric or painted cardboard. Hot-glue ears to headbands to be worn just in front of the wig.
Paint cat eyes, noses and whiskers on each cast member’s face. Use face paint or ordinary make-up, applied with damp sponges. Vary the features slightly according to each character.