Firestone Building Products announced plans to double the size of its Tuscumbia plant, where it makes thermoplastic polyolefin roofing membranes. Fontaine Trailer Co., of Jasper, announced plans for a $5 million expansion and the creation of two new companies, Fontaine Intermodal and Fontaine Renew. Mercedes-Benz announced that it will begin assembling M-Class and GL-Class models…