One of the things I’ve noticed people do in the game is use the tannery not to create leather, but just for the tar. Only the tar. I do it myself and end up with thousands of unused and unneeded leather.
My idea is to have a new building piece called the Tar Pit. It would be fairly large, roughly the size of the Wheel of Pain. The idea is that it is a passive tar generator that uses thralls as the determining factor in how much tar it produces. The fuel is food and thralls (the thralls don’t get used up though).
Here is an example of numbers I think might be balanced (since it is a passive generator).
Thrall slot uses a taskmaster. The taskmaster reduces crafting time. The base might be 120 seconds per craft, while a T4 taskmaster would reduce time to half. The Tar Pit needs thralls and food placed into it’s inventory, just like the wheel of pain, with a maximum of 4 thralls.
For each thrall, you get 1 tar from each craft. For each level above 1 for each thrall, the craft time is reduced 2.5 seconds. At 4 level 1 thralls with no taskmaster, this would be 4 tar every 2 minutes. At 4 level 4 thralls with a level 4 taskmaster, this would be 4 tar every 45 seconds.
As a standard crafting piece with 15 slots for the inventory, this means the pit could hold 1000 tar with 4 thralls and 1 stack of food.
At worst, with only 1 level 1 thrall (and 1 stack of food), the Tar Pit fills in 43.3 hours with 1300 tar. With a full compliment of level 4 thralls, the Tar Pit would fill in 187.5 minutes with 1000 tar. (3 hours and 7.5 minutes).
For comparison, a tannery will make 1 tar every 20 seconds, with or without a thrall. This results in roughly 5.5 hours to get the same 1000 tar, but you will also result in 2000 leather you don’t need.
I think it provides a good place for older thralls as you level and get better ones, and at end game helps ensure you aren’t just making leather for the tar.
You could also just scrap this whole idea and just add actual tar pits to the jungle area you could mine for tar, that could work too. Either way would address the issue of making leather for the tar and throwing the leather away.