As the technology for printing improved over the years, so did the variety and quality of the imprints. These artist picks have become more popular over the last few decades to the point it's somewhat rare to find a famous artist who doesn't use a custom pick. Rick was known to toss out hundreds of customized picks over the course of a single concert. One of the early "mass distributors" of customized guitar picks was Rick Nielsen of the rock band Cheap Trick. Probably the most famous and easily recognizable name on a pick is the logo of Fender Guitars. Many picks have some form of imprint on them from simple manufacturer logos to completely customized artist picks bearing the imprinted signature or bandlogo of the musician. One of the first to make the player imprint popular was guitarist Nick Lucas in the 1930s. D'Andrea Picks was the first company to create custom pick imprinting. Soon after, they requested their names be imprinted on them. All these numbers represent the numbers the Luigi & Tony D'Andrea assigned to each of their new "creations" at the request of the guitarists they serviced. The rounded triangle is the 346 and the small jazz pick, the 358. Most users of picks are familiar with the most popular shape, the 351. It appeared very similar to the real tortoise shell picks the guitarists used in their Greenwich Village neighborhood. The plastic pick was an idea that Luigi, and his young son Tony, Sr., had after purchasing a few sheets of the tortoise shell-like celluloid from a street vendor. Most of today's classic guitar pick shapes were created by the company that made the first plastic pick in 1922, D'Andrea Picks. Pick shapes started with guitarists filing down bone, shell, wood, cuttlebone, metal, amber, stone or ivory to get the desired shape. Reuleaux triangle and a Jim Dunlop Tortex "shark's fin" pick] This shape is, however, merely one of many used by manufacturers. They most often take the shape of an acute isosceles triangle with the two equal corners very rounded and the third corner rounded to a lesser extent. Over time people have made picks of various materials, including plastic, rubber, felt, tortoiseshell, wood, metal, and stone. A guitar pick is a type of plectrum designed for use on a guitar.