By JULIANA BARBASSARIO DE JANEIRO (AP) â¿¿ There's nothing glamorous about the industrial warehouse reverberating with the zap of soldering metal, the clatter of hammers and an earsplitting whine of a circular saw, or in the sweat-drenched workers toiling in the midafternoon summer heat among huge bolts of cloth and heavy-duty sewing machines. Yet it's from warehouses like this one that Rio's over-the-top glitz-and-glam Carnival parades emerge, as they will Monday night for the final round of a two-day performance. The internationally renowned competition between 12 elite samba groups dazzles more than a billion spectators in person and on TV for two days, but it takes nearly a year and hundreds of workers, many of them volunteers, to pull each one together. "We're anonymous artists. The public has no idea who builds all this," said Angelica da Silva Bernardes, one of those working in the warehouse run by the Grande Rio group. She's a telemarketer who cuts her day job to part-time during the pre-Carnival season to help out her group in the afternoons and evenings. "Our motivation is seeing the way people light up when they see our work." Bernardes is part of an army of dedicated workers who spend their days, and, as Carnival approaches, their nights, designing, welding, carving, cutting, sewing and embroidering, all to create a seamless spectacle for others. It's hard work. Grandmothers strain their eyes sewing for hours. Paint-stained young men in old shorts and flip-flops take naps on ratty pieces of foam laid out between work tables in the wood shops after pushing through the night. In the days leading up to the parade, the intensity revs up, and there are fewer breaks. Directing the madness at Grande Rio's warehouse is Roberto Szaniecki, the "carnavalesco," or artistic director, who works in an all-white office on a floor above the work space, surrounded by large computer screens, slick new laptops and a team of architects, graphic designers, clothing designers, theater set producers and other technical help.