Hit a wall with crafting two items together

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Still a bit of a problem. AddUseItemCallback(); per each item. Things like having many sanity potions (1 of the items used, the other being a container of blood) per map were the name would be potion_sanity_1, potion_sanity_2, etc.

You should be able to make use of a global.hps or inventory.hps instead of the map script.