Plastic rhymes with:
thermoplastic, elastic, iconoclastic, inelastic, interscholastic, scholastic, thermoplastic, bombastic, drastic, dynastic, ecclesiastic, elastic, enthusiastic, fantastic, fantastik, gymnastic, iconoclastic, inelastic, interscholastic, monastic, onomastic, sarcastic, scholastic, stochastic, thermoplastic, unenthusiastic
Plastic sounds like:
palisades, placetas, placid's, plastics, plisetskaya, polecats, populists, publicists