Push small squares of cloth into Styrofoam shape with a knitting needle, leaving the edges sticking out. Repeat until the shape is covered. Add hanger and display on tree.
One way to do this is to cut out the desired pattern in styrofoam. Use a round ball of styrofoam for a Christmas ornament or pumpkin. Then wrap the styrofoam with a cloth, covering the styrofoam completely and evenly. Use glue or straight pins to tack the cloth onto the styrofoam.
After cutting your cloth to the desired shapes, use a table or butter knife to gently press the edges into your foam shape, sharing seams between each piece of fabric.
Cloth can be glued to styrofoam with simple Elmer's. You can find free styrofoam if you look. The tricky part is to get the cloth to lay flat on sphere. Make pattern for your cloth by covering a sphere with masking tape then carefully remove it in one piece, slices the tape until it lays flat. There's the pattern.