How to make a costume for my horse?

for 4h i am in a costume class with my horse and i was thinking about dressing him up as a devil but i don't have much of an idea as to how, so far what i've got as an idea is i could get some cloth and form it to fit over his body and neck. i want to spend as little money as possible and not use a super lot of paint otherwise we will have a pink horse for a while. any suggestions on how to do this would be very helpful!?