I have sometimes had to fly out of Boston with various home made (made in my lab really) gadgets. I have never had a problem because I follow the advice of a friend who has much experience with this situation. Here are his main tips as I remember them:

1: Always travel with the power disconnected.
2: Do not place prototypes inside anything that will be opaque to the X-ray machine unless absolutely necessary.
3: Tape your business card showing that you are a research scientist to the outside of carry on items holding prototypes, and to each prototype inside.
4: Approach the security checkpoint with a friendly smile, and say something like "Hey there! I'm a scientist and I am traveling with some equipment. Is there anything special you need me to do?"

I have NO idea why the business cards work, but in my experience they do. If you are, for argument's sake, a hacker or maker without an Institution, why not make up your own nice looking business cards? Or make up your own Institution? I maintain an Institutional affiliation that has nothing to do with my employers for those moments when I need to do something that my employers wouldn't like.

I am afraid that this advice may not extend to artists, but for the scientists out there I hope it helps.

bgarland, thank you for your knowledgeable comments.

it is the issue relating to the showing of ID to the police that most concerns me (some of my research has to do with next generation government issued ID).

are you aware of a good lay-readable survey of the various laws governing the showing of IDs such as drivers licenses and passports?

as you say, such things vary by state. as an international i would like to learn a bit about the spectrum of laws in the US.

i am from new york city originally, and on a recent visit home from switzerland where i now live i was surprised to be asked for my id by a police officer as i was walking down the street during the middle of the day. i did not comply, but spoke politely, and managed to get out of the situation without showing ID, and also with out getting arrested.

this sort of thing would not be tolerated in switzerland, one of the reasons i live here now.

A follow-up thought: does anybody here know of an existing such project, or have the resources to start such a project? I know many people who could contribute expertise, but on the cryptographic and technological side not the legal side.

As a privacy researcher I am always troubled by such stories.

I am a big fan of ACLU literature titles like The Rights of the Suspect, etc. I wonder whether they could be prevailed upon to provide a Right to Privacy title to clarify for us non-lawyers exactly when we are legally obliged to divulge which pieces of our identity.

I am interested in the fact that these results differ from those I researched for the alt.drugs.caffeine FAQ in the early 90s.

I found a reproduction of the list I contributed at http://www.inwa.net/~frog/caffeine.htm (the current version of the FAQ seems to have replaced the list with a pointer to the National Soft Drink Association).

I wonder whether the numbers I got from the National Soft Drink Association by phone in the 90's were inaccurate, or whether the formulas have changed over the years.