Get your starter. The starter's job is to provide acetic acid bacteria, which converts ethanol into acetic acid (the primary ingredient in vinegar). Unpasteurized, unfiltered vinegar. It's important to use vinegar that hasn't been processed in a way that interferes with the acetic acid bacteria. Mother of vinegar.
Pupillary distance. Pupillary distance (PD) or interpupillary distance (IPD) is the distance (the industry standard is to measure in millimeters) between the centers of the pupils in each eye. This measurement is used when preparing to make prescription eyeglasses.
Average PD is about 62mm and most people fall within the 48 to 74 range but average PD for adults is from 54 to 68 mm. For kids, the number is generally from 41 to 55mm. If your number is outside this range, you may have made a mistake. Please do not guess or assume your PD.