Indian De'Signs Leading Metal Letter Sign / Aluminum Letter Sign Makers In Chennai. Aluminum letters and numbers are customs cut out letters from a flat sheet of aluminum. The aluminum lettering cut outs can be used indoors or outdoors and can be used for decorative wall letters or custom house address numbers. The aluminum letters and numbers, typically used for signage, can be painted, polished, anodized or natural satin aluminum finish. Aluminum cut out letters are light weight, easy to install, will not rust and come with a lifetime guarantee.