The easiest tool is Unity. It’s free and has plugins for every SDK including cardboard:
Unity has tons of documentation and can easily import assets from just about everything including OBJ/FBX/Sketchup files. Once you have the basic parameters setup you can push whatever 3D models into your VR environment.
In terms of interactivity, there are lots of options but that may require some level of light coding/scripting or finding some other libraries. Unity makes it drag and drop and there are lots of tutorials, so even if you’ve never written a line of code in your life don’t feel overwhelmed.
Google Daydream may be worth the upgrade if it supports your current phone. Otherwise they make cheapo bluetooth remotes and keyboards which can emulate controls. ex http://a.co/bQujIav