sewing radical (no. 204)
黹 is a rare kanji that primarily serves as a radical (no. 204) related to sewing or embroidery. Its standalone meaning is unclear, but it is associated with needlework.
黹 is an ancient pictograph representing embroidery or needlework, with the upper part suggesting thread and the lower part a stitched pattern. The exact historical development is uncertain.
The top ハ looks like a needle, and the lower part 冂 with 并 inside resembles fabric being stitched. Picture a needle piercing through cloth to create embroidery.
For チ, imagine a tiny needle making a 'chi' sound as it pierces the fabric: chi -> チ, like the soft sound of thread pulling through.