Over the last year, I have done a little bit of this and plan to do a bit more of it in the upcoming season at my chapter (SoMN). It adds a lot to the flavor of the world, plus gives a boost to productionist characters, which is always cool.
1. Make some sheets of some fairly vague tags that can be applied to various different kinds of creature type that can be applied to a variety of mods without needing to get too specific (ie: "Bug Ichor", "Bone Dust", "Chunk of Metal", etc.). If you need a really specific tag for a special kind of creature (ie: "Bloodsilk Spider Saliva", "Fur of the Big Bad Wolf", etc.), then you can simply write up those special tags when the time arises on a blank creature-loot-template tag.
2. Each tag is essentially just coin that can only be spent on a particular production skill (unless someone Merchants it to make it coin usable anywhere, which is perfectly viable for them to do). I pull 200 copper from treasure policy for the event, I can drop 200 production of Bug Ichor. Simple as that. Don't vary their merchant vary from their production value, 'cause as said, that screws up the system. If you plan for it ahead of time (pre-event being ideal), this shouldn't be a drastically big problem, especially if you...
3. & 4. ...keep the specific creature loot tags separate, and don't necessarily do it for every mod/creature. If you rationed out 200 production of treasure policy into 200 production of Bug Ichor, then don't worry about if you go through all of the Ichor on your first of two bug-centric mods. Doing tags like this doesn't need to necessarily replace your current loot-dropping methods; it just augments it and makes it a little more interesting.
It's a little tedious if you try to do it for everything or for mods on the fly, but I think it works out great if you get it all prepped for a small number of specific mods during your weekend ahead of time ("The PCs are going to Snake Cave on Saturday afternoon, so let's take 200 production from treasure and prepare 200 production of Reptilian Scales tags that we'll drop during that mod instead of pulling from our main loot bin." "Sounds great, see you next week at the event!").
1. Make some sheets of some fairly vague tags that can be applied to various different kinds of creature type that can be applied to a variety of mods without needing to get too specific (ie: "Bug Ichor", "Bone Dust", "Chunk of Metal", etc.). If you need a really specific tag for a special kind of creature (ie: "Bloodsilk Spider Saliva", "Fur of the Big Bad Wolf", etc.), then you can simply write up those special tags when the time arises on a blank creature-loot-template tag.
2. Each tag is essentially just coin that can only be spent on a particular production skill (unless someone Merchants it to make it coin usable anywhere, which is perfectly viable for them to do). I pull 200 copper from treasure policy for the event, I can drop 200 production of Bug Ichor. Simple as that. Don't vary their merchant vary from their production value, 'cause as said, that screws up the system. If you plan for it ahead of time (pre-event being ideal), this shouldn't be a drastically big problem, especially if you...
3. & 4. ...keep the specific creature loot tags separate, and don't necessarily do it for every mod/creature. If you rationed out 200 production of treasure policy into 200 production of Bug Ichor, then don't worry about if you go through all of the Ichor on your first of two bug-centric mods. Doing tags like this doesn't need to necessarily replace your current loot-dropping methods; it just augments it and makes it a little more interesting.
It's a little tedious if you try to do it for everything or for mods on the fly, but I think it works out great if you get it all prepped for a small number of specific mods during your weekend ahead of time ("The PCs are going to Snake Cave on Saturday afternoon, so let's take 200 production from treasure and prepare 200 production of Reptilian Scales tags that we'll drop during that mod instead of pulling from our main loot bin." "Sounds great, see you next week at the event!").