@crackwood01
This is a bug of version 4.0.beta2, it only happens if you are using the imperial system.
You may switch to the metric system or downgrade to the latest stable version.

@Dorin
The thickness is initialized to 10 cm, but when imperial system is used the minimum value is set to 1 foot = 30 cm, which is greater than the value, causing the exception. Maybe the minimum should be 1/4 foot (3 inches).

EDIT: we wrote at the same time!