Most acrylic paints need to be thinned before using and so artists use some type of pallet to mix and thin their paint. While some artists simply use a scrap of plastic, an old CD, etc. others go to the other extreme and purchase an expensive and beautiful porcelain pallet. In my opinion, neither are ideal for painting miniatures. An old CD or other flat piece of plastic allows the paint to flow out thinly and then it dries out very quickly. Paint needs a well to collect in and then it does not dry out as fast and you will save on paint. Porcelain pallets, though having wells for paint to collect in, are designed for water colors. Water color artists put globs of their paint into the wells and leave them there for months. When they use a color they simply wet the brush and take some color from the paint blob. For this reason porcelain pallets are heavy, perfect for a permanent pallet as water color artists use. However, for acrylic paint and minis they are cumbersome. An acrylic paint pallet needs to be cleaned after each use, lugging those heavy porcelain pallets to the sink every day is just no fun, not to mention that they are rough on the bottom and can scratch your sink or wooden counter. Also, the wells on porcelain pallets are larger than necessary and so your paint will spread out and dry quicker.
For miniature painting a simple pallet with small round wells is ideal, such as the cheap 2.00 plastic pallet shown below.
A cheap plastic pallet has just one fault and that is that the more worn the plastic gets the harder it is to clean the dried paint off it - but at least they are cheap and can be easily replaced when necessary. It would be great if someone made a small porcelain pallet in the same design, but no one does. I was fortunate, however, in that my dad was a stainless steel freak and hope to be artist in the 70's and he picked up a stainless steel pallet thirty years ago. When I married an artist (Srishtiart.net), he gave her all his unused art supplies including this pallet, which I promptly snuck off with. Stainless steel cleans easily and last forever, unfortunately I have not found anyone who sells stainless pallets, so I use one stainless and keep a plastic in reserve for those days when I use a lot of colors.
Now onto the "Penny Saving Pallet"
One of the headaches of painting miniatures is that you don't need a lot of paint and so those few drops of paint on the pallet dry out very quickly. If you have 3 half-mad children like me, you could also get interrupted at any moment and come back in 10-20 minutes to a dried pallet. To combat the problem of paints drying on the pallet I took some thick pieces of wire and epoxied them to pennies. When I am done with a color on my pallet, I drop one of the pennies on top of the paint and it covers the paint and keeps it from drying out. Twenty minutes latter when I need that color again, I just lift the penny and the paint is wet and waiting. I can even go and feed the kids and watch an hour of TV and come back to some live paint - really, paint will take 1-2 hours to dry up when covered by a penny. The wire serves as a handle which makes it easier to take the penny off the pallet, but just plain pennies will do the job just as well.