Extracting Boric Acid or another flame retardant from stripped Nether logs would just make sense given their lack of flammability.

In addition, tapping Slime Blocks for glycerol would be a good way of getting it without needing to directly add soap-related content.

Thinking of the Tapper more as a simple way to extract fluids from a block without heating rather than exclusively a tree tapper would be the way to vastly expand its functionality beyond simply polyisoprene

Minecraft Username:
FlynnGuy

Fan of this. There will probably a few more ways to extract things from the Nether and End in the future.