This is a basic tilt sensor inspired by ball-and-cage style sensors, but 2d instead of 3d. A captured nickle connects pairs of wires depending on the sensor orientation. These are quick to build, and pretty cheap; I came up with them for a project where I wanted to know which face of a cube was pointing up (a task for which you only need two -- I'll leave that as an exercise to the reader).
The nickle does sometimes catch a bit on the perfboard; gluing something a bit slipperier onto the board, or lightly sanding it, might help.
Step 1: Break the Perfboard
Figure out how many holes apart you will need each pin in the cage to be -- you'd like it to be the case that the nickle only touches two at once, but too much play will waste board. I left six holes between pins, axis-aligned. This was a bit looser than I would have liked. Having the cage slightly diagonally oriented might allow a better fit.
After doing the layout, score and break the board. I score a few times on each side with a box knife and break over the corner of a table. In these pictures I'm making two sensors, so I've made four plates -- a top and a bottom for each. The little bit of extra board was useful elsewhere in the project.