We describe the development and construction of a large screen version of the Cambridge time-multiplexed autostereo display. The new device uses a 50 inch diagonal spherical mirror in place of the 10 inch Fresnel lens of the original Cambridge color display. A fivefold increase in image luminance has been achieved by the replacement of sequential color on a single CRT with separate red, green, and blue CRTs. Fifteen views are displayed at 640 X 480 (VGA) resolution with about 250 cd/m2 luminance and 30 Hz interlaced refresh rate. A 22 mm interview separation provides three views between a typical viewer's eyes, giving a smooth stereoscopic effect over a 330 mm wide eye box. Two identical optical systems have been built, allowing simultaneous use of the device by two viewers. The two system are off-axis with respect to the main mirror, requiring geometric compensation on the CRTs in addition to the normal color convergence. The prototype produces two independent full color, large 3D images which can be viewed under normal lighting conditions.