Archive of the former Yahoo!Groups mailing list: Homebrew PCBs

Hi,
Pardon my ignorance. How can I print Gerber laypout on a
transperency in exact size. Can any laser or inkjet printer be used
or do I need a specific type? And how shall I set the print size to
match my desired layout size exactly without going through trial and
error?
Please help.
Thanks,
JP