[Keystone Construction | Custom & Semi-Custom Homes | Twin Falls, ID Keystone Construction and Development, Inc. has been in the Magic Valley since 2006. During that time, we have built countless homes and developed several residential subdivisions. We pride ourselves in having a trustworthy team where honesty, communication, attention to detail, and daily supervision is the foundation of our business. The owner, Colby Walter, is the only builder in the Magic Valley that has earned the Graduate Master Builder (GMB) and Certified Green Professional (CGP) designations with the National Association of Home Builders (NAHB).]