Hellstone Crate

Every one carries an Obsidian Lock Box, and that is the whole reason to bother. Shadow Chests do not come back once you have cracked them, so after the Underworld has been stripped this crate and its pre-Hardmode version are the only renewable route to that loot pool. If you want a second Sunfury, a Dark Lance for a friend, or a Magma Stone you skipped the first time around, this is where they come from.

The Lava Charm is the one accessory that changes anything, since it feeds the Lava Waders chain and buys you working room down there. The Lavaproof Fishing Hook is the practical pull: it ends the bait problem permanently and lets you keep casting without hunting Underworld critters between every session. The furniture and painting lines are decoration, worth keeping if you are building down there and worth ignoring otherwise.

The ore and bar lines are not independent of each other. A single crate settles on at most one kind of ore and one kind of bar, so you will never see Hellstone and a Hardmode ore fall out of the same box. Treat the metal as a rounding bonus, not a substitute for mining.