Can anyone give me a link to a electronic device that can measure a distance from 4 meters range...
Or how to make one.

I searched the term "measure up to 4 meters distance" and found this:

https://www.google.com/search?q=measure+up+to+4+meters+distance&ie=utf-8&oe=utf-8&aq=t&rls=org.mozilla:en-US:official&client=firefox-a

And this is one of many:

New Fluke Laser Distance Meters instantly, accurately measure up to 100 meters (http://www.eetimes.com/electronics-products/electronic-product-releases/test-measurement/4389827/New-Fluke-Laser-Distance-Meters-instantly-accurately-measure-up-to-100-meters)

Thank you very much... big help.. I hope its available at local stores