To render plastic

What does "to render their conceptualisations plastic" mean in the following context? Does it mean "to rpresent their conceptualisations in a formable manner"?

Context:

This preconception of advertising as a visual medium persists despite the continued relevance of strap-lines and short pieces of body copy, and has been strengthened by the emergence of several major campaigns in the late twentieth century that operated successfully without words. Art, on the other hand, has become increasingly conceptual, with a significant number of artists readily presenting their work through the medium of words, despite the continued need to render their conceptualisations plastic in some way. The move into sometimes purely verbal works of art has been aided by a purposeful recuperation of the word in art over the last century.