I have two versions of flat stand-up Wirt display cases, and a more traditional Paul Wirt fountain pen countertop sales display case. The first Paul Wirt countertop store display case was featured in a 1908 catalog ad, pictured below, and sold with an assortment of Wirt pens. My stand-up flat cases are both missing the arms (legs?) on the sides that allow it to stand up tilted back. The first is top loading, and features a pin in the back that locks into a ring at the bottom of the inner portion of the case. The second features a tilt away front.
This second case is similar, but this model has a front that tilts open to access the pens.