This app tricks the app store into thinking you have a different device, a Nexus 7 for instance.
This doesn't change your build prop and using it is dead simple. Run it, choose the device you wish to emulate from the drop down list.
click the link for google dashboard, which registers the device as the one you are emulating. Go to play store, download the app you want.
When you're done, reboot the tablet or go back to the mrket helper app and choose restore.
It works as advertised.