The ornamental design for a metaldetector, as shown and described.
FIG. 1 is a top perspective view of a metal detector incorporating my new design with the remainder of the metal detector shown in phantom;
FIG. 2 is a left side elevational view thereof; the opposing side being a mirror image thereof;
FIG. 3 is a front perspective view thereof,
FIG. 4 is a back elevation view thereof;
FIG. 5 is a top elevational view thereof; and,
FIG. 6 is a bottom elevational view thereof.
The broken line showing of structural features is included for the purpose of illustrating non-claimed subject matter and forms no part of the claimed design.