By jadedResearcher. Special thanks to paradoxLands for additional coding (especially the ability to save and load to images), and to karmicRetribution (for user testing).

Knowledge gained from:
  • Weaving 2/1 Twill on a Rigid Heddle Loom, by Sylvia Emard on her blog "I Dyed it My Way"
  • Inventive Weaving on a Little Loom, by Syne Mitchell
  • Weaving on 3 shafts, by Erica de Ruiter

    • A v1, non rigidHeddle specific version of this tool can be found here.
    * Note: Any pattern that only goes UP or NEUTRAL in the second heddle can be replicated via a single pickup stick.