New toy! Fritz Obermeyer’s Jenn makes stereographic projections of most of the convex uniform tilings of the hypersphere; of the 64 Conway-Guy polychora only four (whose construction is somewhat anomalous) are missing.
I downloaded the generic Unix version and easily built it on my Mac.
The author has responded cheerfully to my comments.
Without looking, I guess the missing four are the grand antiprism, the snub 24-cell, the snub cube prism, and the snub dodecahedron prism.