I've used this round glass palette for quite a while. I believe it's original purpose was meant to be as a table topper. It's heavy and thick, about 16" in diameter, and the edges are beveled and smooth. There is nothing wrong with it other than it seems a little bit small when I'm working on a larger canvas.
For my new palette I'm using a glass kitchen counter protector. It has a crinkly surfaced top, but the bottom is smooth, so I flipped it over. It also has smooth beveled edges. There were little silicon pads on the bottom four corners which I found easy to scrape off - really easy, I just lifted an edge with a fingernail and then they just peeled off. I then stuck them on the other side - the side that was the top and is now the new bottom. The rectangle fits well on the table next to my easel and provides a lot more room for mixing. Here it is, below, in use.
The colors at the moment, from the lower left corner and moving clockwise, are as follows: Titanium White, Hansa Yellow Deep, Cadmium Orange, Quindracinode Red, Venetian Red, Raw Sienna, Raw Umber, Grey Green, Olive Greem, Terre Verte, Cerulean Blue, Cobalt Blue, Ultramarine Blue, and Mars Black.