Step 16: admire your product
When all the toluene is gone and you can't smell it any more (it smells like rubber cement), you will be left with a tiny amount of greenish liquid in the bottom of your container that smells strongly of that familiar minty, catnip smell. I got 143 mg, which represents 0.03% of the 1 lb of catnip I started with. That may not sound like a lot, but it's not far off from the 0.3% theoretical maximum yield given the improvised apparatus. And a little goes a long way.
Furthermore, this material is extremely pure. I analyzed it using gas chromatography/mass spectrometry, and found it to be >99% nepetalactone (see the second image below). In the chromatogram, nepetalactone is the giant peak around 12 min with a molecular weight of 166, and it's the only peak that is visible. For comparison, a sample of "catnip oil" that I purchased online was only about 80% nepetalactone (third picture).
If your sample has any amount of solid material mixed in with the liquid, most likely that is nepetalic acid. You may see that if you chose to omit the base wash from step 13. It's OK and isn't going to harm anything.