Erik wrote:
"Maybe you can use a mercury switch (2 electrodes in a clsss tube with a drop of mercury)."

Yes, that's what I was thinking of as a "tilt switch" - they're listed in Farnell, RS, etc.

(the use of mercury is doubtless deprecated these days, but there are alternatives available)

Here's another idea:
put a magnet on the "bob" of a pendulum arrangement, and use reed switches (or Hall sensors) to detect its "swing"
You could use various numbers of switches to detect different angles.
Might need some damping?

I s'pose you could do a similar thing without a magnet but using a slotted opto detector instead; maybe the wheel out of an old mouse...

etc etc!