The achilles heel of pinhole photography when your camera resembles a bomb. Very nice, open-minded people (always female and with children) stop to ask what the hell I think I'm doing. Phone calls were placed, but the exposure only lasts 90s.
I'll get some pictures of them up eventually, they are green (now black) 50 cal ammo boxes. They fit two 4X5's side by side. Haven't tried to get them on an airplane yet.