Base for holding glass ornaments. Glass ornaments shown from Lowe's. I find that the ornament stems aren't perfectly round, so I heat a hot spot in the center with a glue gun or soldering iron, make a depression with a pencil and let it cool a bit, then insert the ball.

I'm using these to hold clear glass ornaments in a cabinet. I then fill the thin "stem" of the ornament with hot glue and insert an LED, which can be wired through the channel back to a control board.

I've found these look kind of magical on their own, and they diffuse a single LED really well over a large area for even coloring when mounting behind paper.

I'll set up a series of these in a shadowbox (found at Michael's) and use them as notification indicators for a few of my favorite services with open APIs.