All materials used in Fused Deposition Modeling must have a melting point between 180 to 220 degrees Fahrenheit. Thermoplastics and ceramics are most commonly used. Here are some examples of possible materials that could be used:

ABS (Acylonitrile Butadiene Styrene) Plastics
Investment Casting Wax
Zirconia Alumina
PEEK (Chopped Carbon-Fiber Reinforced Ploy Ether Ether-Kentone)
PMMA (Polymethylmetharcylate)
MABS (Methylmethracrylate Acylonitrile Butadiene Styrene) Plastics.