Help with density measuring device

[COLOR=#333333][FONT=PT Sans]Hi every one i hope someone can give me an idea how to achieve that. I am working for at school project, where i am trying to build a device that measure density of a multilayer object/enviroment. I am thinking to achieve that by measuring the axial force exerced while pushig the device inside the multilayer object.[/FONT][/COLOR]
[COLOR=#333333][FONT=PT Sans]But how exactly to do that, and what sensors i have to use - i cant really figure that out.[/FONT][/COLOR]
[COLOR=#333333][FONT=PT Sans]any one can help ?[/FONT][/COLOR][IMG]http://www.engineersedge.com/engineering-forum/attachment.php?attachmentid=1354&stc=1[/IMG]

So, density is equal to mass divided by volume.

Please describe what you are measuring in terms of mass and volume with this method..

I understand the poster is a student. It sounds like what he is really trying to measure is viscosity. I recall that it took me a while to understand the difference between density and viscosity.

Thanks guys for the answers, i figured out. i made it complicated for my self. i found an easier solution :)