flag, banner
幢 centers on a piece of cloth used as a symbol or signal: a flag or banner, often carried or displayed to represent a group or convey a message.
幢 combines 巾 (cloth) with 童, which likely contributes the sound and may relate to a child or servant, but the exact historical reason for this combination is uncertain. It is used for a type of banner or flag.
The left side 巾 is a cloth, and the right side 童 looks like a child standing under a roof. Imagine a child holding a long cloth banner at a festival: 幢 is a flag or banner.
For トウ, picture a tall flagpole with a banner that reaches the toe of a giant statue: toe -> トウ, and the banner flutters high above.