Just send it in a Postal Priority box and write “ORM-D” on it. You are not “the shipper” according to DOT regulations and bear no responsibility for its packing or certification. Even the questions they ask you won’t stand up in a court of law unless you have been trained or certified.
These items may not be sent in U.S. mail:
Air Bags
Ammunition
Explosives
Gasoline
Marijuana (medical or otherwise)
