I shipped a porthole with uship. I was the sender, so I was responsible for the packing, which is probably 75% of the battle. I put it on a skid, bubble wrapped it twice, built a box over it, bubble wrapped that, then shrink wrapped it. Then I put some L-shaped corner pieces on the top and strapped it to the pallet. Then I sat back and bit my nails until I heard from the buyer
All went well though. It arrived with no damage.