Start with a circular wooden plaque. Find these at Michael's, Hobby Lobby, generally any art supply or craft shop will have these. Starting with a coarse grit sandpaper and work towards a smooth finish. It will help if you use more than one grade of sandpaper. Once it feels smooth to the touch you can begin applying black chalkboard paint. It will take some time ro dry.
Using a rigged up compass I painted the rings, adding a second coat by hand. The inner squares were added easily once the circles were dry. For the white paint I used Citadel Ceramite White, but any acrylic will do fine. Since it is chalkboard paint you can also try chalk or a white charcoal pencil instead. I used a white charcoal pencil to add the symbols and Latin text.
The candles were made from Aves' apoxie sculpt and painted Citadel Mephiston Red. Bottles were fodder. This was made for my John Constantine custom, but could be used for just about any magic based character. I'll post the link for a full set of images and detailed how-to in the comments if anyone is interested.