I went to college in Chicago and fell in love with White Castle and back then you could get their "bag of burgers" which was 10 for a $1. We had them again when in Michigan back in 2004.
You could always take something like a veggie corer and make the required "5 holes" and cook them with some thinly sliced sauteed onions under the pattie after the first flip with the bun on top to steam (you steam one half before and the other after "THE FLIP" keeping both buns on top of the pattie and you're in business then.
Larry