Do you know how to use a heat tool and embossing powder? You can find it in the scrapbooking aisle at craft stores. It takes some practice, and it is a time-consuming process:
Print your items on your printer and IMMEDIATELY -- meaning, while the printer is still spitting out the paper, while the ink is still wet -- sprinkle on embossing powder. This powder is available in all colors, some with glitter embedded. I love the stuff.
Dump the extra powder onto a paper plate, tapping to remove all the excess. This excess powder is still perfectly good, and you can use it on the next invitation. When you're done, return all the un-used powder back to the container; it's too expensive to waste, and until you "melt it", it's still re-usable.
Do not stack the invitations at this point. You don't have to do the melting immediately, but if you brush the letters with your finger, you will lose the embossing powder.
Use a heat tool -- buy this at the craft store too -- to "melt" the powder. Do not over-do it, and do not get the heat tool too close, or you'll cause the paper to "warp". Allow to cool. You now have raised print. The embossing is also permanant; you can put your invitations into the envelopes or stack them without fear of damaging them.
This works best when printing on vellum paper (because the ink dries more slowly).
Again, this is time-consuming. Do not assume you could pop out all your invitations in one evening.
