Tabi, refers to a style of Japanese sock or boot, which resembles a mitten for the foot, with a split separating the big toe from the rest. Tabi boots or "jika-tabi," such as the kind that may be worn as part of a ninja costume, differ from tabi-socks by the presence of a soft protective sole. Any pair of socks may be converted to tabi style with a simple sewing alteration and made suitable for outside wear by the addition of a custom sole. The advantage of tabi is that they allow the wearer to grip with their toes and thus improve balance -- especially useful when climbing like a ninja.
Put the socks on and mark with chalk the gap between your big toe and the rest of your toes. Remove socks.
Cut along the chalk line, creating a notch in each sock, and turn the socks inside out.
Sew along the notch with a running stitch, following the "V" shape you have created on both socks and turn socks right side out.
Place the chamois or leather rough side down and stand on it with your foot flat and your feet bare. Trace around both feet with chalk to make an outline of your soles.
Cut out sole outlines and stand on them with bare feet. Mark a line between your big toe and the rest of your toes for each piece.
Cut a notch along the chalk line on each sole outline. Attach to the soles of the socks, rough side down, so that the toe split in the sock matches the toe split in the sole. Adhere with a thin, even coating of waterproof fabric glue and allow to dry completely.
For more flexibility, try thick, textured rubber as an alternative sole material.
Be cautious with sharp needles and scissors to avoid injury. Leather soles provide no protection against sharp objects. Avoid stepping on broken glass, pottery or metal edges.