I have a requirement to create 2 plastic hemispheres - 14" and 13" diameter.

I'm new to vacuum forming, although I've been happily CNC milling and laser cutting for some time.

My question is how much plastic (in X and Y) would be required to form the two hemisphere?

Low detail, so 1/16" thickness plastic would probably work OK?

I'll be making the "plugs" using CNC egg-crate process, filled with fine plaster.

All advice gratefully received.

Thanks,
Steve