An "On_Craft" trigger

I would like my players to receive an extra item for Crafting certain blocks/tools.

Since it's already been 8 days, I don't know if you are still having that problem.
For now, you could try out the "RecipeManager" plugin, that lets you do (nearly) all the crafting-related stuff you could possibly imagine.

...this doesn't really seem to go with what OtherDrops is.