Lack Easy-Off Leg Stackers

I liked the concept of the original "lift off table" legs from zuspiel, but I wanted them to meld into one another even more seamlessly.

So I popped into F3D, pushed the lower leg assembly edge in by 2mm, and extruded the top leg assembly around it, leaving a .5mm gap. Otherwise, though, the model is unchanged.

Works perfectly with [this drill guide](https://www.thingiverse.com/thing:2117852)