Many BB8 are available on the net. I made this simplest one that really works. By work what I really mean is stand by itself.
Step 1: Materials
Foam balls for the body and the head
Nut from an old spare
Colors to make the BB8 classy
2 part polymer clay
Step 2: Make the Head
Cut the smaller foam ball to make the head.
Cut a section and carve the corner to a tilt.
Step 3: Attach the Head to the Body
Glue the head to the body. You may have to cut a small section on the body to get a flat surface. Let it dry.
Step 4: Add Magic to Make Him Stand
Find the center at the bottom. Mark a circle which can hold the nut. Carve the place for the nut to adjust properly. Flush in the nut. use some glue if the hole is large and the nut tries to fall over.
Step 5: Cove Up
Mis small amount if the polymer clay and fill the hole and cover the nut and let it dry. Sand the place to make it look even if required.
Step 6: Make the Antenna
Find something to make the antenna. I used the bottom of the paint brush for the antenna. Poke the antenna in place and glue it properly.
Step 7: You Are Done
Your desktop BB8 wobbly toy is ready. Let everything dry properly. Color it as you like and enjoy.