"Packing 78rpm records so they will break in shipment"  -Wyatt Markus, EdisonDiamonDisc.com

The Post Office is very aware that many
people are taking advantage of the low
Media Mail rates to ship OTHER ITEMS
that are NOT media!  They OPEN and
YOUR RECORDS and RUIN your perfect
packing job!

It goes without further explanation that 78rpm records are fragile.  To the uninitiated, it can be very discouraging to ship these valuable
artifacts of history just to find that they have arrived BROKEN or CRACKED.  The main key in shipping 78rpm discs is that they remain
FLAT and are protected from being flexed.   So, I have a few  ideas for you!

1.  If packing ONE record, you will want to cut 8-10 11"x11" pieces of cardboard, and place the record in the middle of the sandwich.
Wrap tape around it tightly, and put a label on top of the stack to let the new owner know that the record is in the MIDDLE of the pieces of
cardboard, and that tey should unwrap carefully.   Take the inner package and place it in a larger box that allows 1"-2" of space on all sides and
fill the void with packing peanuts and/or bubble wrap. 

2.  If sending more than one record, stack them together, wrap the stack tightly in plastic wrap (Saran Wrap or light duty kitchen kling wrap). 
When the records are stacked together, you are creating rigidity that protects the records from flexing.  After wrapping in stretch wrap, put a plastic
grocery bag over the stack, then wrap in tape to keep the stack straight and under light compression.  Wrap further in bubble wrap, then place in larger
box that allows 4"-5" of spacing around the stack.  Fill around stack with styrofoam peanuts or bubble wrap.  Pack tight, and use a good box.