A locked element and methodology are provided for use in a block diagram model of a graphical modeling environment. For example, single crystalline c-plane GaN can be grown on Cu substrates with MOCVD. A constant low rate of infusion is created upon removal of a test chamber from a surgical handpiece. An operating flange is formed on and extends from a fitting front end of the wall portion of a hood portion. The product dispenser still further includes a tower structure that is removable without disabling the product circuits, and a method of merchandising on the tower structure. The system may be attached to or integrated within another instrument such as a guitar, keyboard, autoharp, pedal steel guitar, sitar, koto, mbria, and pipa, among others.