"She and I went over all kinds of ideas," said Aaron Mills, of Elizabeth, about the costume their horse, Blue Angel wore at the Colorado Horse Park's sixth annual Halloween with Horses Oct. 22.

Arien Mills, 11, rode Blue Angel to a third place ribbon.

"I train horses and knew if anyone could carry a billboard, (Blue Angel) could," said Aaron Mills.

Mills has trained horses for a total of 13 years and serves Parker, Franktown, Elizabeth and Kiowa with his business, AaronMillsHorsetraining.com.

"We thought we'd make (Arien) a painter and got to splash her with paint. That was the funnest part," he said.