HOUSTON--(BUSINESS WIRE)--Changing Technologies, Inc. (OTCBB: CHGT) is ready to go “old school” with its latest proposed venture: 3D printing of obsolete spare parts. Obsolescence has long plagued manufacturers and customers. Manufacturers don’t want to stockpile aging spare parts for discontinued items as it can be expensive to store and leave them holding unsold inventory. Customers dislike obsolescence because they often have to discard otherwise still-useable items simply because one vital