Small, colorful, fusible plastic beads can be placed on a solid plastic-backed peg array to form designs and then melted together with a clothes iron; alternatively, they can be strung into necklaces and bracelets or woven into keychains. Fusible beads come in many colors and degrees of transparency/opacity, including varieties that glow in the dark or have internal glitter; peg boards come in various shapes and several geometric patterns. Plastic toy beads, made by chopping plastic tubes into short pieces, were introduced in 1958 by Munkplast AB in Munka-Ljungby, Sweden. Known as Indian beads, they were originally sewn together to form ribbons. The pegboard for bead designs was invented in the early 1960s (patented 1962, patent granted 1967) by Gunnar Knutsson in Vällingby, Sweden, as a therapy for elderly homes; the pegboard later gained popularity as a toy for children. The bead designs were glued to cardboard or Masonite boards and used as trivets. Later, when the beads were made of polyethylene, it became possible to fuse them with a flat iron. Hama come in three sizes: mini (diameter 2.5 mm), midi (5 mm) and maxi (10 mm). Perler beads come in two sizes called classic (5 mm) and biggie (10 mm). Pyssla beads (by IKEA) only come in one size (5 mm).