Humtown Products Produces UNItube, the Ultimate Blow Tube System   COLUMBIANA, OHIO - Humtown Products, Inc. manufactures the patented UNItube blow tube system, an economical system that presents many unique advantages over traditional blow tubes.   UNItube blow tubes are made from impact-resistant plastic, which absorbs stress due to misalignment without damage to the core box. They can easily be cut to accommodate virtually any flow rate, thus eliminating the need to stock several sizes. UNItubes are inexpensive, easily installed, simple to replace, totally adaptable and uniquely flexible.   By contrast, metal blow tubes are expensive, and a different tube is needed for every size and application. Worse yet, because of their rigid construction and inflexibility, misaligned blow tubes can result in damaged core boxes - literally chewing up profits.   Humtown also offers the UNIplug, a tube with a thicker wall that allows the installation of a core vent for use as a gassing or tamping tube.   Humtown Products, Inc., is a core making and pattern making firm located in Columbiana, Ohio.