Step 4: Building the head
Unfortunately, I forgot to take a picture before I put on the paper mache, so you'll have to imagine what the ribbed cardboard looks like.
The downside of the ribbed method is that the ribs show through. so it is going to get several coats of wallboard joint compound to make it more spherical.
In hind sight, I should have spent more time looking for a balloon. The ribbed method never got perfectly spherical.
To give the paper mache more strength, I coated the inside with a layer of expanding foam.
Between the cardboard, hot glue, paper mache and a lot of wallboard joint compound, the head is getting rather heavy.