I wanted to make a hollow ball out of washers because I thought it would be fun. I tack welded a few different sizes of washers around a 3" wooden ball from the hardware store. The wooden ball made a good form to start with and using TIG welding meant I could control the heat well enough to avoid burning the wood during welding.

Once the metal shell ball was all together and the wooden ball was trapped, I used a MAP torch to light it on fire to remove the wooden core. Unfortunately this is the only photo I took from this project, and I no longer have the end product. I still wanted to share because it's a very cool photo.