San Francisco's Fulcrum Knives has taken inspiration from these slender forms of currency to come up with a compact everyday carry option that can be slipped into a jean pocket, and then flicked into action with one hand when the need arises.
The Eclipse knife might be small, but it's actually made up of 24 individual parts. Leading the charge is the Wharncliffe-style blade made from heat-treated stainless steel. It features a pointy tip for piercing, a flat edge for chopping and a shallow chisel grind for smooth slicing.
With a simple button release and locking mechanism, the 0.7-inch (1.8-cm) blade can be deployed with one hand and secured in place. The moving parts pivot on phosphor bronze washers said to offer greater longevity, while the grip is crafted from a sturdy combination of fiberglass and epoxy.