wine flagon
鈄 centers on a specific type of wine vessel: a flagon or handled container for serving wine.
鈄 combines 金 (metal) with 斗 (a measuring ladle or dipper), suggesting a metal vessel used for wine. The exact historical development is uncertain.
The left side 金 is metal, and the right side 斗 looks like a ladle or dipper. Picture a metal ladle-shaped flagon used to pour wine.
For トウ, imagine pouring wine from the flagon into a tall toe-shaped glass: toe -> トウ.