(a) Business use. Section 4218 of the Code applies to the use by a person, in the operation of any business in which he is engaged, of a taxable article which has been manufactured, produced, or imported by him or his agent.

(b) Personal use. The tax on use of a taxable article does not attach in cases where an individual incidentially manufacturers, produces, or imports a taxable article for his personal use or causes a taxable article to be manufactured, produced, or imported for his personal use.