This paper describes a simple 3D display that can be built from a tablet computer and a plastic sheet folded into a cone. This display allows naturally viewing a three-dimensional object from any direction over a 360-degree path of travel without the use of a head mount or special glasses. Inspired by the classic Pepper's Ghost illusion, our approach uses a curved transparent surface to reflect the image displayed on a 2D display. By properly pre-distorting the displayed image our system can produce a perspective-correct image to the viewer that appears to be suspended inside the reflector. We use the gyroscope integrated into modern tablet computers to adjust the rendered image based on the relative orientation of the viewer. The end result is a natural and intuitive interface for inspecting a 3D object. Our choice of a cone reflector is obtained by analyzing optical performance and stereo-compatibility over rotationally-symmetric conic reflector shapes. We also present the prototypes we built and measure the performance of our display through side-by-side comparisons with reference images.