This cube was truly a work of frustration and love. The following is a VERY condensed description of how I got to the end result. 

The whole project took about 80 hours hands on time, but over 2 months to complete because I had to put it down or I would have thrown the thing at a wall out of frustration.

The first thing I did was try to explain to friends and family what I planned to do. Which in a nut shell was to carve a block within a block of wood. I got a lot of "Yeah right"s, and "There is NO way!"s. But that only fueled the fire in me to prove 'em wrong..

I started with a solid block of wood.
Then carved four of the sides into the Triquetra. The two other ends were carved into the Tree of Life. All of the sides were carved to the thickness that I wanted all of the walls to be. Then the frustrating carving on the inside of the block began. I kept one side attached so I didn't have to chase the inside block around getting it to the size I wanted. When I was pretty close, I carved the last side of the inner block away from the last wall. Then I chased the inner block around carving it trying to make the inner cube even on all sides. 

Then I put a natural finish on the inner cube and stained the outside.

The end result was a small inner cube inside a larger cube. It rattles around freely inside. (And they said it couldn't be done...)