making books or scrolls
幀 centers on the craft of assembling books or scrolls, specifically the process of binding or mounting pages into a finished volume.
幀 combines 巾 (cloth) with 貞, which likely contributes the sound. The character relates to using cloth in bookbinding or scroll-making, but the exact historical development is uncertain.
The left side 巾 suggests cloth or fabric, and the right side 貞 looks like a bound stack of pages. Picture using cloth to bind pages into a book or scroll.
For テイ, imagine a tailor carefully binding a book with cloth: tailor -> テイ, and the tailor's work makes the book complete.
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