Alvin - Plastic Engineer Scale - 12 inch - Alvin Plastic Architectural Scales are Professional Triangular Scales. These are professional-quality scales made from high-impact plastic with white, non-reflecting, dull-matte faces and tapered edges. Machine-engraved graduations and color-coded furrows. Supplied in hard plastic case. Alvin is one of the primary sources for drafting supplies and drawing equipment in the country. Creative Coldsnow is a pround retailer of Alvin graphic arts, drafting and fine arts products.