When students interested in having an indoor climbing wall needed expertise on how to construct it they didn't have to look far. Colby's Physical Plant Department carpenters modified an existing design and then spent 350 hours assembling the structure. Result: more happy customers.     "We get our satisfaction from building what the customer, so to speak, needs," said Jeffrey Tuttle, who worked on the climbing wall for an entire month last year. "Often, what they need they can't go out and buy."     Typically, the carpenters are asked to build shelving or cabinetry to fit unorthodox spaces or for specific functions. These custom applications occupy about 80 percent of Tuttle's time, he says, and the requests come from all sectors of the campus. "No two projects are alike," Tuttle said. "We've built everything from the podium they use at Commencement to the special shelving in the multicultural room at Cotter Union."     They even build furniture. When the communications office needed a special table for its designers, with an unusual arrangement of pigeonholes and drawers, the PPD carpenters produced a birch piece that, if purchased, would have cost hundreds of dollars. And they did it in a week.     Tuttle and a crew currently are renovating the Marchese Lounge in Cotter Union into a pub expected to open in February. When they're finished they will have left another imprint on the campus. "That makes you feel good," Tuttle said.