OtterBox, the Fort Collins-based company that is the nation’s leading cellphone casemaker, is bringing jobs back to the U.S. from China, moving 15% to 20% of its volume back to the U.S. over the past year. By 2020, there will be 2.5 million to 5 million direct and indirect manufacturing jobs returning to the U.S., according to an estimate by a global management consulting firm.