In a few weeks I'll be doing an overseas trip with my Brompton inside a semi-rigid suitcase - this weekend I found a suitcase that fits the Brompton if I remove the saddle from the seatpost.
The suitcase's exterior seems to be polycarbonate or something not super-stiff. It has a bit of flex, which seems to help in fitting the bike's protruding parts.
Does anyone have recommendations for actually packing the bike and clothes around it? I'm thinking of wrapping the bike in plastic to avoid getting oil on the clothes, and putting some padding around the parts that actually touch the suitcase. But should I pay particular attention to any one part of the bike?