Metal area?

[Gleamie]

I've been trying to find the place where metals spawn but so far nothing. Anyone knows where it is?

[Dmlsys23]

There isn't one.  There is LV200 island, LV500 island, LV800 island, and the Dead Sea.  In the post-game more areas open after talking to Enah at the Guild.

[CoarseDragon]

Metal monsters can sometimes be found in tbe 500 area.

[Cainohpue]

Yeah, the metal monsters are a pain to find this time. Here's where I encountered them (from strongest to weakest):

Metal Dragon: Nibill False Tomb
Metal Behemoth: Nibill False Tomb, level 800 area
Metal Ceratops: Nibill False Tomb, level 800 area, level 500 area (most commonly)
Metal Dryad: Kiron False Garden (if I remember correctly)
Metal Turtle: Aigaion Wilderness
Metal Kiwi: in the earlier dungeons

Apart from Metal Ceratops in the level 500 area, I think it's easier to encounter metal monsters inside the dungeons. Each dungeon/area is assigned a tier in which (only) certain special monsters appear (more commonly). Just use the Attraction Tube until you encounter a metal or gold monster. If you, for example, encounter a Metal Dryad, you'll probably need to switch to a weaker dungeon/area to find a Metal Turtle.

The easiest way to fill the big box/rock bestiary entries is to summon these boxes/rocks (by spending 10 Glowstones) via the Attraction Tubes, though they can also be encountered randomly in dungeons and on the world map (very rarely).