Fold marks on invoice

[Del Miller <..hidden..>]

Is anyone out there using some sort of fold marks on the LaTex Invoice
document?

It's a little thing but it'd be nice to have a fixed-on-the-page mark
(1/3 the way down the page) that allows me to fold my invoices
consistently for mailing.  It's also be nice to have the body of the
invoice start below said mark.   I've searched high and low through all
kinds of LaTex tutorials/sites and can't seem to come away with a clean
answer as to how to get this done -- perhaps I'm not looking for the
correct terminology.

Anybody have any suggestions?

Regards
Del