How to actually alter what is required to craft an item:
The relevant section is this part of each entry:
<Requirements>
<Requirement shpLootObject="2257" iNeeded="3" />
<Requirement shpLootObject="255" iNeeded="0" />
</Requirements>
For each TYPE of item you will need a separate line. The last line always needs to be Requirement shpLootObject="255" iNeeded="0". These lines will show the icons of the items needed in the crafting display (remember the TEXT display of what is needed is handled separately)
The entry
shpLootObject="2257" refers to the disID of the shop item required for crafting. In this case shop item 2257 is the Tibetan wolf skin.
NOTE - you could try adding non-animal and plant items as requirements to craft something. I have successfully used various ammo, grenades, arrows and other gadgets as requirements to craft items. One thing I pondered over and discussed with another modder was creating a series of items you could pick up off of enemies like "Duct Tape", "Super Glue", "Scrap Metal", "Leather Straps", etc etc and having these as requirements to craft various backpacks and such. Ultimately this idea was scrapped as it could lead to frustration for the player if the random number gods decide not to bestow this specific loot. Maybe however these items could be sold by the store if it could be figured out how to add other store tabs/areas (although in retrospect I suppose you could try adding them to the ammo tab if nothing else). Again this is all theory and would all require experimentation to see if it could be implemented correctly.
iNeeded="3" is obviously how many of those you need. In this case 3 of them. For my mod I made all of these 5.
IMPORTANT - you can assign as many items and item types as you like BUT there is a limit of FIVE (5) total items which will be displayed by the crafting display. Everything over that causes a visual glitch and your player cannot see the items which are required. Worse the text description will unlikely match and then therefore you will be unable to tell the player (in game) exactly what it is he needs to collect vs what he has actually collected.
That's why I limit myself to only using 5 total items despite wishing it could be much more. Yes you could always tell the player in a readme file with your mod, but trust me no one RTFM (reads the f*cking manual)
One final note is not to mess with <Levels> or <UpgradeLevels>. These components could theoretically with the correct nomadobjects and archetype adjustments allow multiple "levels" for each crafting tier (i.e 10 or 20 levels of a wallet for example), but at the moment they do not allow this to work. Of course if you wish to experiment with this please be my guest and please share your discovery if you get it working. I've always wanted to have multiple levels of upgrades so that the player would have more reason to continue hunting.