spade, shovel, trowel, scoop
鏟 centers on a flat-bladed tool for moving loose material: a spade, shovel, trowel, or scoop. The meanings all share the idea of lifting or shifting something with a broad metal blade.
鏟 combines 金 (metal) with 産, which likely contributes the sound and may relate to producing or bringing forth, fitting a tool that moves material. The exact historical development is uncertain.
The left side 金 means metal, and the right side 産 suggests production. Imagine a metal tool produced for digging: a spade or shovel.
For サン, picture a sandy beach where you use a shovel: sand -> サン, and the metal spade scoops up the sand.