try this simple method so you dont have to use you hand to see through the augment reality stuff

Step 1: Things Needed

1. Google cardboard or dodocase vr Kit

2.scissors

3.some nice soft cardboard

4. pen/marker

5.stapler or walcro or any thing u can fix the cardboard

6. lot of creativity

Step 2: Set the Limits

Now its time for measurement.

basically i am an indian, so my ear sixe differes

so it your task to define ur size between the ears and the possible case distance

now mark that in the cardboard and draw a small outline

Now cut the cardboard using an good scissors

make sure there is no sharp edge(it will cause damn unease)

now make sure both are equal.

Now first place that in your ears and see how comfortable you feel,

now place your VR kit and see what distance its matching and mark it with the pen/marker

now attach the cardboard and VR kit and stapler it or glue it or tape it

now its ready

So simple right!! so start cutting!!!