As eol says, for bulk records a heavy box is the answer, but for single records it doesnt work because the weight of the box pushes the package over 500 grams and into the expensive post options, making the single record too expensive for buyers.
For single records I cut two squares of heavy 2 or 3 core, stiff cardboard slightly larger than the record. Simply pack between the sheets and tape right around the edges. It pays to wrap the record sleeve in plastic cling film to prevent the tape from sticking to the edge of the cover and to protect from moisture if safe dropped.. But heres the important bit...... make sure the flutes in the core of the cardboard run at opposite directions to each other. This gives the parcel the rigidity and strength to prevent bending. The whole thing then weighs under 500 gm. and goes as a small parcel for just under $9 postage cost.
I have only ever had one complaint with this system and that was for an old, brittle, bakelite, gramaphone record ( rare 1930,s blues American artist ) that cracked in transit. Never lost a modern plastic record with this system.
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