I have read about the Brompton B-Bag, an expensive travel bag that provide only 5mm of padding. The other option (so I thought) is the "koffer" suitcase... also expensive but worth considering if you travel often with the Brompton. I thought I would test the B-Bag and be able to make a quick judgement of whether or not it was practical... but they didn't have any in stock. Instead, they had free Brompton boxes! Yay!
We taped it to the back of my bicycle and I had an awkward heelstriking ride back to the train station.
My life is all about boxes right now.