S is a Physicist skill, which summons a S shaped object. It can be hooked to planks, among other things without the need of a nail.

This is most commonly used by shamans to build a car.

Map 217 has a bridge of S objects.

v · d · eShaman
Modes	Normal mode Hard mode Divine mode No-skill mode
Items	Arrow  Spirit  Balloon  Rune  Small box  Large box  Anvil  Short plank  Long plank  Ball  Trampoline  Portal  Cannonball  Ice cube  Conjuration
Skill trees Spiritual Guide Wind Master Mechanician Wildling Physicist Other  Nails (anchors)  Indicator  Orbs  Totem