Faucet nut hand wrench

thingiverse

This provides extra leverage for removing those big plastic nuts that are commonly used to hold faucets to sinks. They're supposed to be hand-tightened, but there may be some gorillas hiding amongst the plumbing workforce because it's not uncommon to run into an example that's tightened beyond reason. This will help give that extra bit of leverage you need while hopefully being small enough to fit into the cramped spaces favored by the bottom of faucets.