Or use a cut-down cardboard box. Pin, staple, tie or sew the cloth to the frame. A traditional recipe for batik wax is a mix of beeswax and paraffin, about 60 40. Paraffin is more brittle, and lets dye penetrate wherever cracks form. Crackle is a characteristic batik effect, a scatter of thin dark wavy lines, a batik hallmark.
Some dyers seek crackle, freezing and crumpling the cloth to make more.
Others avoid, if they can, any effect that seems uncontrolled. For more crackle, more paraffin. Beeswax should be light yellow or tan and clear of debris. But most batik today is done with synthetic micro-crystalline waxes. They usually fall between beeswax and paraffin in price and in working properties.