Complex sentence: All three wooden coasters were designed by Curtis D. Summers and built in-house by the Taft Broadcasting Company, despite some sources that claim Philadelphia Toboggan Company (PTC) built these coasters, as PTC stopped building coasters in 1979.
Split into simpler sentences: All three wooden coasters were designed by Curtis D. Summers and built in-house by the Taft Broadcasting Company. Some sources claim Philadelphia Toboggan Company (PTC) built these coasters, but PTC stopped building coasters in 1979.