I did drill a hole into the glass for my last similar project. I sealed it up with transparent silicone and I was very happy that it didn't leak. At least this is what I thought at the moment. Several months later I noticed that the power brick that I had under the desk was all greasy and it was having an oily aspect. When I was putting my hand on it I could feel my fingers oily afterwards. I realized that the oil was very slowly leaking through the core of the threaded wire from the jar into the power brick below.