Most of the soap is made fresh when you order and will shrink as it cures.
Soap that is wrapped with a cigar band label will eventually become loose.
The only packaging we have found to work exceptionally well are these kraft boxes.

They measure: 3-13/16 x 2-3/4 x 1-3/16
Oval cut-out measures: 2-1/6" x 1-1/4"