Prior to 1996, each model was cast from a grey material and covered in a coat of paint corresponding to the base color of the finished model. The details of the model were then painted onto this layer of paint, resulting in a loss of the finer sculpting detail due to the thickness of the paint on each finished model. Beginning in 1996, each new model was cast from a pigmented material corresponding to the base color of the finished model. The details of the model were then painted directly onto this material, resulting in greater detail and a less shiny appearance. In 1997, most older models received updated molds that utilized color vinyl, and some were repainted with new color schemes, while a few others were retired. Despite the modifications, the eighteen remaining models retained the same model numbers as their predecessors. This became the cause of some confusion as a single model number was used to refer to two versions of the same model, which was particularly noticeable with the new color schemes for Stegosaurus, Triceratops, and Pachycephalosaurus. Color name tags were also designed and attached to each model in place of the original folded paper name tags.