Answered my own question. From the Plastruct Catalog...
HEAT FORMING
Heat forming, shaping and bending plastics can be done easily in as simple a device as a kitchen oven, provided that the
upper heat range can be controlled. The most widely used plastic sheet materials for forming are ABS, Butyrate and Styrene.
A new material which also has excellent forming properties is Copolyester plastic sheet. The best temperature to work with
these materials is approximately 200° - 25O° F (120° C), and, unless you actually want to melt the material to a near liquid, don’t exceed about 400° F (205° C) under any circumstances.