A seat-belt-restraint-system for a vehicle occupant seated in a vehicle seat. When the recording medium mounting detection unit detects that the recording medium is mounted, representative information that represents recorded content on the recording medium is acquired from the recording medium and displayed on a display unit prior to file analysis by the file analysis unit. Then, photometry is made while inactivating a strobe, and an exposure value is determined based on an object distance. A preferred method includes operations to generate a watertight digital model of a hearing-aid shell by thickening a three-dimensional digital model of a shell surface in a manner that eliminates self-intersections and results in a thickened model having an internal volume that is a high percentage of an external volume of the model. The method includes a number determining step, a remaining-time determining step and a transport order skip step.