In article , "David Forsyth"
writes:

On a second side note - does anyone happen to know what the formula would be
to calculate the capacitance between two metal plates of a given area and
given spacing, having an air dielectric?

From the good ol' "Green Bible" (ITT Reference Data for Radio
Engineers, 4th Edition, 1956, page 133), for only two plates,
dimensions in inches, air dielectric:

Capacitance (pFd) = 0.225 x Square Area / spacing

Assuming the plates are the same size and shape.

Len Anderson
retired (from regular hours) electronic engineer person