For a relatively simple arcane/summoning circle to make, get a piece of paper and a dark pen, a sheet of wax paper, tacky glue, white glue, a hot glue gun, gravel (Aquarium gravel size is a good one), and fine sand.
On your paper, you want to figure out the size of what you want. A good idea is to have what you want summoned on hand to figure the internal dimensions. Start with a circle big enough for it to fit inside easily. Then you want a pentagram inside it with a joining pentagon between the points that match up with the outer circle. Make sure the lines are dark and easy to see through the wax paper.
Tape your wax paper in place over the pattern so that it doesn't move around.
Put a line of tacky glue around the circle, you want it to be just outside it. Arrange the gravel as well as you can to make the best circle you can, then pour some sand over it in order to fill the gaps and make it look better in the end. Let it dry as best you can, then use watered down white glue and cover the ring.
Once that dries, take your hot glue gun and trace the rest with a decent sized bead. You want enough for it to be solid and yet not disruptive to later play. This includes an inner rim along the circle itself there. When it's fully cooled and cured, brush the entire thing with white glue and let dry before peeling the entire thing off the wax paper, then brush white glue on the underside to make it more solid.
Once that dries, prime and paint.