A recent post about a missing emissions canister got me thinking, here in England we aren't required to have any such control but that doesn't stop the unpleasant petrol fumes from the fuel tank on a hot day. So I came up with an alternative using a Pipercross in line crankcase breather. It doesn't return vapour to the engine but absorbs them by utilising active carbon and plugs into the fuel tank breather pipe. The notation for the first image - 'A' inline crankcase breather, 'B' crankcase vent open ended.

Been thinking of a similar setup myself just to eliminate the fumes in the garage. There are many cheap carbon canisters to choose from.