Very generous of you, hednic. I believe it should be as simple as sending them via USPS Ground and slapping an ORM-D label (or handwritten in marker) on the parcel. If you're physically dropping them off at Post Office, check "Yes" when the screen prompts you asking about perfumes, liquids, etc. They probably have ORM-D stickers at the PO as well.
If you're sending them within CONUS from within CONUS, you should be good!