Hi guys and welcome to my first instructable.

I bought a new water pump to the well and I needed to protect it from running without water. So, while waiting for a delivery, I decided to make a simple protection switch from the components i found at home.

The idea was to use the microswitch deactivated by the weight of the bottle of water when the water level is too low and activated again when the water level is high.

Part list:

Wiring box
Aluminum sheet
Plastic sheet
Microswitch - activated when released
Spring
Double sided bolt with a smooth shank
Washers
And a few bolts and nuts to hold it all together

Step 1: Reversing the Microswitch

The microswitch I found at home was activated when pushed and deactivated when released, so I needed to reverse it's function.

I made it by interchanging one of the pins with the plug.

Step 2: Sheets and Box

I was cutting the sheets with the saw instead of the shears, because you won't get a straight plate with the shears.

I cutted two pieces of the aluminum sheet. One to push the microswitch and one to tie the string.
The hole in the pushing plate has to be a bit wider than a double sided bolt to work properly. The pushing plate also has to be a bit narrower than a microswitch to move freely.

I also cutted two pieces of a plastic sheet. One for the base plate and the other one for the cover plate.
Drilled holes are made to attach the plate in the box, for the microswitch and for the pushing plate.

The hole in a cap of the wiring box is drilled a bit smaller than a double sided bolt to seal the mechanism from the humidity.

Step 3: Completing

Here you can see completed but uncovered mechanism and mechanism with the cover plate.

Note the spring and the washers. I had to use it, because the microswitch can be initiated effortless, so the weight of the string could push it and a small hole in the cap will not allow to release the button.

It's also useful to oil the shank of the double sided bolt to ensure a smooth move.