The only mud I ever came accross with that had its own crafting system had it set up so, that the items made, deteriorated over time. So you either had to go to a repair-NPC to have them repaired or if the item finally broke or vanished, go find the items needed to create a new piece of equipment. No idea if this is something to consider or if it was already mentioned, not gonna reread the whole FAQ-post again. Or if it's something worth for a player to actually learn but then you go back to the whole trust-issue, but that's beside the point now.
If my memory is correct you just had to collect the needed pieces, put in a command and you had your handmade equipment. Not really sure if mini-games or lenghty scripts as Kvetch already mentioned will keep the player's attention, especially not if you have to go through the whole mud to pick up just that particular item you need for whatever it is you want to make. (A huge world can be a drawback at times.) And yes some people that play, prefer to be self-efficient without having to depend on other players to get this or that.
But my other question is the cooking-part. When I started playing here, all those years ago, all I wanted to collect was Ma Brown's recipe book and start cooking. Well that didn't work out well, seeing the thing wasn't implemented.
Anyway food in 4d, in my opinion, doesn't really serve a purpose. Ok, it helps regenerating your ...points faster but as a mort I went to fill the largest drinkcontainer I could find at the milkfountain east of Recall, go to my recovery-hide-out or waited for a restore. Otherwise I just turned off the 'you are hungry/thirsty'-messages.
In other mud/games, food is used to restore health, which in 4d is done with potions.
So how will you convince players to actually go find Ma Brown's Recipe book and start cooking if all you need to do is go drink milk till you're full?