Thought that a head strap might be a nice touch for the DoDo Case Virtual Reality Viewer. I used some velcro straps to make sure you could adjust it to different head sizes.
If the viewer instructions are giving you trouble, check out this nice instructable on getting the viewer put together:
Step 1: Supplies: What You'll Need
DoDo Case Virtual Reality Viewer
Optional: Bubble wrap or felt
Step 2: Measure Your Head
The easiest way to do this is using a soft fabric measuring tape. But, if you don't have one of those, yarn will work just as well.
Cut a piece of yarn about a foot long.
Hold one side of the yarn on your right temple, and stretch the yarn to the back of your head using your other hand.
Measure that distance using a ruler.
Add 1 inch to that measurement, and that is how long your two side straps will be.
Use the same process to measure from your forehead, over the top of your head, to the back of your head.
This time add 2 inches to that measurement.
This measurement is how long your top strap will be.
Step 3: Make Your Straps
Cut a 4 inch strip of duct tape, and place it sticky side up.
Cut another 4 inch strip of duct tape and place it sticky side down on the first strip of duct tape.
Offset the second piece so about 1 inch of sticky is left on each side. Turn this assembly over.
Attach another 4 inch strip of duct tape (sticky side down) to the assembly of duct tape. Turn this strip over.
Continue until your strap is as long as the previous step requires.
Measure the distance of extra sticky side facing upward, and cut a piece of duct tape to stick (sticky side down) onto it.
You should be left with a strap that has 1 inch of sticky side facing down, and the rest non-sticky.
Complete this step two more times until you have 2 side straps (both the same size), and a top strap (which will probably be a little bit longer).
Step 4: Attach the Velcro
Attach your straps to your completed virtual reality viewer.
One on the left, one on the right, and one on the top.
Cut four strips of Velcro. Two of each type.
The strips should be about 1 inch by 4 inches.
Adhere the Velcro to your straps.
The Velcro on the left strap should be placed on the outside of the strap, facing away from the viewer.
The Velcro on the right strap should be placed on the outside and the inside (one will attach the side straps together, and the other will attach the top strap to the side straps).
The Velcro on the top strap should be on the inside of the strap facing toward the viewer.
Step 5: Wear Your Awesome Sauce
Attach the Velcro strips of the side straps behind your head.
Pull the top strap over your head and attach it to the Velcro on the back side of the side straps.
Wear your adjustable viewer with pride (and share with a friend. After all, why would it need to be adjustable if you are the only one who is going to use it?)
Step 6: Optional Comfort Consideration
The nose section of the viewer isn't necessarily comfortable against the bridge of the nose.
Use some bubble wrap or a length of felt to add some much needed comfort.