Ships sizes

I am contemplating the possibility of eventually planning to consider
(you
get the idea, right?) casting mini's (in acrylic/polyester resin...I
work
for a plastics company).  In order to get an idea of how ruinously
expensive a fleet I can build, I'd like to get an idea of what size
figures
people associate with the various ship classes.  If they're built on
about
the same proportions as the FSE or ESU ships, (original designs,
though!),
what length would you pick for a DD? CH? SDN?
I'd pick something like .750", 1.25" and 2.50" myself, but just in case
I
a) actually get around to this project, and b) ever see another gamer in
person instead of by e-mail, I'd like to have compatible sizes.

Email off list: laserlight@cwix.com.  If people demand it, I'll post to
my
website the responses.