I was inspired to make my own mercury glass jewelry tray after failing to find one that I liked in stores. The basics of this project are similar to my mercury glass pumpkin. It’s just easier since you’re working with a flat surface.
The only supplies you need are a spray bottle filled with a 50:50 mix of water and apple cider vinegar, a can of Looking Glass Paint
Just spray a layer of paint on the bottom of the glass. Wait about a minute, then spray with the water/vinegar mixture. Repeat both steps until you’re happy with the results. You can use a paper towel to blot the water/vinegar mixture between coats for a more paint dappled appearance. 
Rubber adhesive bumpers keep the tray from sitting directly on the counter.
As a bonus, the bumpers look like little crystal feet for your tray. 
That’s all it takes to make your own mercury glass jewelry tray!