First you need to buy all of the things listed in the Components list. (I'll have pictures/videos for the steps soon)
Once the beach ball, canvas, and newspaper arrive you can get started with the build! Get some glue and water and make a two parts glue, one part water concoction. With that made you can start gluing your first layer onto the beach ball! Do three layers of newspaper, one layer of canvas, and then one final layer of newspaper. Once it's all dried you can start on the next step!
I would suggest doing this step while step 2 is drying. Get your Styrofoam ball and cut it in half one inch from the center. Most Styrofoam balls have a seam at the center, so just grab a ruler and make some marks one inch from the center and cut away!
Now you can discard the smaller half of the Styrofoam ball.
Get the larger half of the Styrofoam ball and use a lighter to melt away the center. be sure to do this outside, because the fumes are repulsive. If your having a hard time melting away the center with the lighter I would suggest using a soldering iron. It takes longer, but its much more precise. IMPORTANT: make sure you cut at least one inch from the edge!
(This picture shows the following step completed as well as this step)
Now you need to make a bezel (an special edge) use a knife or other tool to cut at an angle from the edge of the half-sphere to the center mark and go all the way around.
I didn't do a very good job, but that's okay because I can cover up the mistakes later with wood putty/filler.
Once the beach ball finishes drying out a layer or two of wood putty / wood filler on it
now put a layer or two of wood putty on the outside (including the bezel) of BB-8's head