Golf balls and ping-pong balls

Such comparisons have never made much sense. Dimension such as inches and centimeters should be quite familiar to all lay persons. If the size of something needs to be described, use common units of measure. Trying to use objects invokes inaccuracy in tranlating the size to the object, then compounds the potential error of interpretation when the patient uses their best reconing of the object to their size.

Inches as a unit of measure isn’t rocket science; if the patient cannot understand this then not much else is likely to improve their understanding. We’re not talking obscure units of measure (angstroms, ergs, pecks etc.)