Thermoreversible gelcasting (TRG) is an attractive net-shape powder-based processing technique which relies on the temperature-driven gelation of a polymer solution. This study uses the TRG of alumina to investigate the implications of triblock copolymer design (block length, endblock fraction, and midblock chemistry) on rheological and green body properties. The liquid-to-solid transition and relaxation time in the gel state are controlled by the polymer's endblock length while the total polymer length controls the viscosity at high temperature. Although triblock design and concentration do not affect the green body porosity or sintered density, they do have significant effects on green body behavior. Triblocks with a high fraction of rubbery midblock behave as elastomers and confer significant toughness to the green bodies. In contrast, those with glassy midblocks increase the strength of the body but also behave in a brittle manner. Green body strength increases with increasing triblock concentration and is well described by a model for the strength of ceramic bodies with the binder localized at the particle necks.