In this home movie, Dell is performing her adaptation of the Nekko Omar Perfect Mystery, a prop created by William "Doc" Nixon in the early Thirties. She vanishes or produces a rabbit from an apparently empty box that has been suspended between two uprights.
Nixon's props were expensive in their day, and this one was advertised as virtually self-working. That term, of course, is a misnomer. It meant that a prop didn't require specialized sleight-of-hand skills to operate, though no effect is good without a masterful presentation. And that's where Dell shined as a performer.
It's likely that Dell owned more than one Nekko Omar Perfect Mystery, as she often bought multiples of her apparatus so that she could replace them as she wore them out. Dell was hard on her props, which had to endure rough and frequent handling.That's why her husband, Charlie Carrer, often reinforced them, frequently adding a shiny Krinkle Krome exterior that resisted fingerprinting. It's visible in this video. Charlie was a master mechanic and metalworker and thus an essential partner to Dell, besides being a brilliant juggler in his own right.
—Michael Claxton, with thanks to Gabe Fajuri and Phil Schwartz