Vaccuforming Question

Hi All,
I'm not sure if this is where this question should be posted, so I apologize if not. I'm looking to vaccuform a 16" hemisphere. with the idea being that I make 2 of them, seal them together, and have a ball (I'm building a 80% sized BB-8). However, I'm at a loss for vaccuforming the ball. What should I sue to create the buck? I looked for a 16" styrofoam dome but couldn't find one. Since this thing needs to roll, it has to be a near perfect sphere. Thanks for the input!

Are you int he US? If you search 16" acrylic globe, there are some lighting shops selling them for under $40. They have an opening but perhaps you can use those? I'd be inclined to buy a couple, make a template for BB-8's panels and then cut them all out. How many you'd need would depend how big the hole was vs one of the circular panels.

Good call! I found one for $25. I think these things will work quite nicely. Thank you for the help!

The Prop Builder's Molding & Casting Handbook by Thurston James (a fantastically useful book overall) has a section on this. You don't make a buck, you make a circular cutout of the needed diameter in a box of adequate depth and just pull vacuum until you have half a sphere. Alternatively if you don't have a deep box to vacuum into you can inflate the styrene with compressed air.

Google Books link