Andi Kovel and Justin Parker of Esque Studio in Portland, Ore., found freedom in blowing molten glass vases simultaneously and joining them before they cooled. At that point they continued blowing to puff up the size of the now double vase, which they call Pushmepullme. “The forming is a choreographed dance of fire, molten material and movement, and we both know our part of the dance to the point of pure instinct,” Ms. Kovel said.