This is a fix for dwarves with preferences for impossible-to-produce materials, such as penguin teeth or rat leather.

This is in two parts, a Python script which automatically modifies a set of raw files, and a set of vanilla raws which have been so modified.

In vanilla DF, many creatures have craftable materials (such as teeth and leather) which cannot be produced at all in the game. Some creatures have materials defined which are not present in any body part on that creature, such as teeth in birds. Other creatures have those materials in their bodies, but are too small to yield them when butchered. This does not stop dwarves from having preferences for these materials, and you can frequently end up with nobles mandating material that you could never even in theory produce.

This script parses the entire raw objects folder. It examines each creature and determines what materials can actually be produced in-game from that creature, by butchering or other means. It also examines each creature to see what materials are defined in that creature that might appear as preferences of your dwarves. Materials which shouldn't exist at all, such as bird teeth, are deleted. Materials which are required to exist but aren't possible to produce are changed to 'useless' forms which are functionally the same but will never appear as preferences.

To use this mod:

If you are using the vanilla raws, just copy the contents of the 'objects' folder over to the 'objects' folder of your DF install.

If not, install Python 2.7 on your computer, then run the included script. It will prompt you to locate a folder. Select the 'objects' folder of your DF install. The script will run, and create a 'processed_raws' folder. Copy the contents of this over back into your 'objects' folder.

The script will also, as it runs, produce an output indicating for each creature what is produced when that creature is butchered, and what changes it is making to the raws as it runs.

Note: This will only work for 31.25. It is almost certainly not going to work for any later version until I update it.