Lye from soap to bio fuel to Crystal meth, LYE (KOH, potassium hydroxide) Has a 1001 uses. And it is soooooo easy to make you could almost do it by accident !
Here's what you need

FIRE!
WATER!
WOOD!
3 PLASTIC BUCKETS

Step 1: Step One: Apply Fire to Wood

First thing you need to do is burn some wood, No pine only hardwoods, Apple and fruit trees is the best.
Now after burning that wood collect the ashes in a big 5 gal plastic bucket make sure the coal are not hot and melt through the bucket.
Fill the bucket about half way should be enough.

Step 2: Step Two: There's Holes in Your Bucket

Take one of the plastic buckets drill some small holes into the bottom, then take some flat rocks cover the bottom of the bucket, then on top of those rocks add a layer of gravel.

Step 3: Step Three: Just Add Water

Take the empty bucket this should be the biggest bucket,label it LYE so no one tries to use it.
Take the bucket with rocks and holes and put that in the other one. Fill it with the wood ashes.
Now just add water, this must be soft water or distilled water, the best to use is rain water.

Step 4: Step Four: Your Lye Is Done

That's it! Once the water drains through the ashes filling the bottom bucket with LYE water, To increase the acidity of the lye, take the water and pour it through the bucket again and again.
   You can test the acidity with a PH meter make sure it goes from 1.0 - 14.0 14 is the PH level for making soap.
   Old ways of telling if you lye was ready for soap making was it could dissolve a chicken feather, or if a egg is placed in water it would float above the water like a bobber.
    Or you could boil it, DO THIS OUT DOORS!