The ornamental design for a faucetbase, as shown and described.
FIG. 1 is a perspective view of a faucet base showing my new design;
FIG. 2 is a top plan view thereof;
FIG. 3 is a left side view thereof;
FIG. 4 is a front side view thereof, the opposite side being a mirror image of the side shown; and,
FIG. 5 is a bottom view thereof.
The broken lines showing faucet spout, sprayhead and handle are included for the purpose of illustrating portions of the faucet that form no part of the claimed design.