In addition to the bloody nails, Snake asks you for a bucket of blood.
The recipe for the bucket of blood is then added to your church workbench.
- 10 blood
- 3 flitch
The amount of blood needed is large but fortunately, it is required to extract it to improve the quality of new bodies at the morgue.
This is a practice that should be done almost systematically on all new bodies.
There is a good chance that you have accumulated a large amount since the beginning of the game before entering this quest. Personally 15 units had been deposited in my chest over time naturally, before starting the quest.