When Randy Roberts opened Z Art Department a few years ago, he decided to focus on artists important to Colorado's history, including Herbert Bayer, Roland Detre and Winter Prather, all of whom are dead. Then last year, he delved into contemporary art by living artists. One of the first exhibits of this kind was Parson in Perspective, which looked at a decade's worth of work by important local sculptor Chuck Parson, who creates conceptual abstractions made of sheets of steel, panes of glass and hunks of stone, with the finished pieces held together by nuts and bolts from the hardware store. Z Art Department has kept a low profile, but that is starting to change with crowd-pleasing efforts such as this one.