Although we do not print "stamps" per se., we do have first class postage that is printed on a label with your Ship To and Ship from address on it.

The same as a stamp - but with a printed address label.

You do have the option of printing directly on a envelope, or on a  sticky label, or you can print the label

on regular paper and tape / glue it on. Sticky labels does make it easier but are not required.

Here are samples of different sizes of  postage labels and how they would look.