Hello,
I'm an amateur electrical engineering student.
I want to embed LEDs into this Vortex Pocket Arrow and have them light up when the ball is thrown.
I need a small switch that will complete a circuit when the ball is in motion, similar to an accelerometer.
Alternatively I could just use a regular switch but I think it would be cool if it the lights were triggered by motion.
I plan on 3D printing a small cylindrical housing for a AAA or AA battery and circuit and to put the LEDs inside the whistles.
What are some components I should look into?

 

vibration switch. you can buy them or make your own using springs. You'll have to figure out how to keep it from oscillating. Jeeze I had to scoll down a lot because those pictures are so big, you can resize them and if we need to see details, can click on them.

 

It just so happens I have one on my desk. This was in a throw ball that has a cracked case and was outside in the rain for some time.
The dirt has not stopped this working, amazingly enough.
You can see the spring that is soldered on a bit above the board, and when dropped, it hits the pad under it to trigger the flashing LEDs cycle.

 

You could use a tilt mercury switch, with 555 timer .