Summary

Ever wanted to use your smartphone as a FPV screen ?

There are plenty of solutions using Googles cardboard headsets with a binocular vision.

The drawback is that the screen resolution is de facto divided by 4 as the two left and right images are twice smaller.
Another inconvenient is that not all drone softwares allow these dual screens display.

A few "single lens" option did exist but are hard to find.
See this link for more details : https://mavicpilots.com/threads/using-single-len-fpv-goggles-for-mavic-mini.78219/

So I decided to make one using a cheap magnifier headset for electronics.

I choose the "2LED headband illuminated magnifier" model. Search on google, it is really popular and cheap.
Be sure to get the model with detachable leds and x3,5 magnifier (see attached picture)

Then you can print this thing;

slide the base into the led casing, screw a M5 screw to block it in place, attach the phone holder with the knob (another M5 screw),
attach the bottom parts on the phone holder (2x M3 screws).
Slide your phone (Samsung Galaxy S7 or similar format). secure the bottom parts with a rubber band.
Use the x3.5 magnifier (the strongest one)

And enjoy First Person View with crisp full image in front of your eyes.

The only minor drawback is that the phone weight induces a torque up/down on the helmet.
Simply attach a little 200g weight on the back head screw of the headband, in your back, and you will get perfect balance again !

Try it it is really cheap and really provides a perfect image "full screen" without need for 3D viewing models.

You can "finish" it by adding black cloth around the frame in order to get a perfect immersion.

After you FPV flight, remove the phone, then the phone holder and you can reuse the device for your electronics hobby !