DS+R developed several casework systems for the museum. One is a modular table with a kit of parts that can be locked together in a variety of configurations. Some of the parts have glass bonnets that can be sealed air-tightly to accommodate the preservation requirements of certain artifacts. The bonnets are set on hydraulic activators for easy opening. In some cases the glass is laminated with a PVB interlayer for security and a coating was added to reduce reflections. Other bonnets are made from acrylic as a cost saving measure. Some table parts cantilever off of the main frame, such as in the case of interpretive signage. The legs are made from flat bar stainless steel and are very heavy to keep the tables from tipping over when the bonnets are lifted or in case a visitor decides to use one as a seat. Even still, certain tables had to be equipped with wheels that swing down to transfer loads to the floor when the bonnets are open. The stainless steel legs are finished with a No. 4 grit sanding process done in a circular pattern to give it a soft appearance.
While the weight of the casework was important from a safety point of view—some cases are as much as 2,000 pounds—it had to be carefully managed to stay within the allowable live loads of the building’s floors. The Carnegie Mansion has a steel-framed structure, but it was not built as a museum. The larger cases have frames made from aluminum instead of steel to cut down on weight. One such case is found in the former billiards room. Throughout, DS+R worked with Goppion to minimize the detailing and to conceal the hardware as much as possible, but this was especially successful in this large case. Here, a five-sided glass bonnet rests in a black cuboid base of powder-coated steel panels. The base hides two scissor jacks connected to electric motors that lift the bonnet up for accessing and changing exhibition objects. When closed, it is almost impossible to tell how exhibitors work on the display. “It was important to make this case as elegant as possible, even when we have to support a great amount of glass and steel,” said Buettner. “We designed it to almost sit there effortlessly. Instead of a door, the whole top of case can lift up, close to ceiling, to access the objects in the case to clean, or rotate, or change them.”