Below is a list of Aluminum Trim manufacturers from Walnut, California. Aluminum trim is used in the decorative architectural aspect of construction. Its shape is long, thin and narrow, and it can be custom made to fit a specific purpose or space. However, aluminum trim is also stocked in a range of standard sizes as well. Mostly used in outdoor applications, aluminum trim is weather resistant, meaning it can withstand both high and low temperatures, won't rust when it comes in contact with water, and won't corrode easily.