Do you know of any simple measuring instrument which I can construct?

Question

Please make it interesting and please state how I could go about making it.
I would really appreciate your help.

Answer 1

you could make a balance

you know, like a see-saw with a tray at each end

then if you had a known mass (like a small weight) you could measure the comparative mass of other things

Answer 2

Make a compass!

You will need:
1. A needle
2. Bottom of a Styrofoam coffee cup
3. A big dish with water

Then:
1. Turn the needle into a magnet by using another magnet -- stroke the magnet along the needle 20 times.
2. Place your float in the middle of your dish of water.

Refer to howstuffworks.com - how compasses work?
This is a great website for fun ideas in all areas.

HAVE FUN! =)