There are 2 thoughts in Scuttles
1. Smaller that keeps the brush more in-closed where you build the lather in a bowl and put the lather full brush in to it.
Advantage: Keeps the lather Hot
Disadvantage: Two piece system
2. Larger scuttle that you can build your lather in that will keep your lather warm if to big not at all.
Advantage: One piece system
Disadvantage: Heat Loss
Cast your Vote. Large or Small