Open Press LTD: A 15-Year Anniversary was a short course in the recent history of printmaking in Denver. The show, presented at the Gallery of Contemporary Art at the University of Colorado at Colorado Springs, was an enormous survey of the fruits of the fine press founded by master printer Mark Lunning. Over the years, Lunning has facilitated scores of artists in making thousands of prints in Denver. The daunting job of winnowing the selections down to a manageable number fell to the GCA's longtime director, Gerry Riggs, who created an exhibit that included a big chunk of the contemporary-art scene around here.