Intro: Tilt Activated Switch
It's a 3 position SPDT switch that closes (on) when tilted. Made with 3 pieces of plastic, a washer, and three machine screws + nuts. I made this switch as a hack for a cheap r/c car controller, inspired by the wiimote controlled car.
I just realized, this can also double as a pedometer or a shake sensor
See the Hand Motion Controlled R/C Car Instructable
Step 1: Materials and Tools
two #8-32 machine screw, 3/4" long
four #8-32 machine screw nuts
one #10-32 machine screw, 3/4" long
two #10-32 machine screw nuts
a sheet of 1/8" thick TRANSPARENT plastic, lexan or acrylic can be found in home depot
a washer, 5/8" wide on the outside, with a 3/8" hole in the middle
a 1-1/2" doorknob hole saw (it's a special drill bit, see picture)
a 1" forstner drill bit (or flat wood bit but i am not sure if it works)
a drill, drill press is best, and some standard drill bits
metal files, a thin round one and a larger flat one
Step 2: Prepare the Washer
Take the washer, and roughen up the inside and outside edges. This will make a good electrical connection.
Step 3: Plastic Disk
You need to make two plastic disks. Do this by using the drill with the doorknob saw bit.
Step 4: Plastic Ring
Make two more disks, but before you do so, use the forstner bit to make a large hole.
Step 5: Final
The nice thing about making it this way is that you can let it activate at a specific angle. Another way to make a tilt switch like this is using a ball bearing inside a tube, which is very sensitive.
Since you are making a SPDP (actually SPCO according to wikipedia, since it has a "all off" position) switch, you need to put it together and see where you need to drill holes for the contacts. Stack the disks and ring with the ring and washer as the middle layer (bolded for those who do not understand). Put the #10-32 screw through the center and tighten it. Now you can rotate it and see where you should drill your holes for the contact screws (this might actually take some CAD work if you want ultimate precision).
Drill the holes with the drill bit, and screw in the #8-32 machine screws. Tighten everything with a nut, connect some wires to the three screws, and secure each wire with another nut.
To assemble it, stack it in this order
washer (inside the ring)
tighten with screws
You can drill more holes so you can choose the angle later
Test it with a multimeter
You are done, now you can connect the wires to a R/C car controller