Plastic is suitable for both pencils and drawing pens. Modern types include ballpoint, rollerball, fountain and felt or ceramic tip pens. Tools such as pens and pencils mark the drawing medium. Suitable for both graphite pencils and technical pens. Effects not generally associated with ballpoint pens can be achieved. Marcel Bich was involved in developing the production of inexpensive ballpoint pens. Retailers continue to sell fountain pens and inks for casual and calligraphic use. Some fountain pens are treated as collectibles. Tumi also supplies accessories such as belts, pens, and electronic equipment. Inks intended for use with fountain pens are water-based. Bamboo pens are one of the oldest pens used for calligraphy. A patent for an ink cartridge system for fountain pens was filed in 1890. The reservoirs of the earliest fountain pens were mostly filled by eyedropper. Writing with fountain pens remained a convenience until the 1980s. More than half the steel nib pens manufactured in the world were Birmingham-made.