While building some of my costumes, I've often encountered the problem of not being able to see out of the headpiece or helmet, either because the materials that were easiest to work with or that were the most realistic ended up being completely opaque, and impossible to seamlessly substitute for a transparent alternative.

Even sci-fi costumes that utilise metallic tinted visors often fall victim to this problem, because materials such as tinted window foil are difficult to apply to compound curves without vac-forming, so it's common to see "visors" sprayed gold, but with a small window cutout that has been backed with window foil.

In my case, I was trying to find a viewing window solution for a more organic texture, making it impossible to disguise convincingly. After ruling out colour matched mesh windows and inverted periscopes, I settled on a completely digital solution which closely resembled a FPV drone racing setup.

My target budget for this solution was $40 or less, and as I found out there were a few alternate options that could bring the price down as low as $15-20.

Step 1: The Components

Parts list:

Cheaper wired option (Replaces both the 5.8GHz Camera and Receiver):

2m, 2.0MP USB OTG Borescope - $8.19

If a using a phone with a Type-C USB port:

Type C Adapter - $2.24 or...
Type C Adapter with power input - $1.99

With the exception of the borescope, these are the actual parts I purchased, so I can attest to their compatibility. The wireless receiver for the 5.8GHz camera will cause a reasonably high power drain on your phone, which is why I included the option for an OTG cable which allows a USB power bank to be attached at the same time. Both the wired and wireless options can be found cheaper or more expensive depending on the camera resolution or features. WiFi cameras are also an option worth considering, but are typically larger and may have higher latencies, though they won't require an additional receiver.

Step 2: Benefits & Drawbacks

There are pros and cons to each solution, as well as common issues shared by both. A brief list for each is as follows:

Wireless:

PRO: Can be mounted externally if no cable passthrough is possible
PRO: Potentially lower latency
CON: Higher power draw
CON: Inferior quality analogue image
CON: More components to create mounting points for

Wired:

PRO: Fewer cables to manage
PRO: More discreet camera module
PRO: Higher quality digital image
PRO: Cheaper relative to comparable specced wireless cameras
CON: Longer camera will protrude further if mounted in front of a flat surface
CON: Potentially higher latency
CON: Cables may have to traverse articulated or disconnected parts

An external power source may be required for long term use, although running from a phone's battery should provide at least a few hours' worth of use in both cases. As mentioned previously, a usb splitter or OTG cable with power passthrough will allow you to further increase the usage time. Low latencies (The time delay between what is being captured and the screen displaying it) are necessary to avoid dizziness, with anything over 50ms (0.05 seconds) being likely cause discomfort. Latency can be tested by pointing the camera at a stopwatch or high refresh rate timer and photographing both the timer and phone at the same time: The difference between the two is the time delay.

Step 3: Camera Mount

The rest of this instructable assumes the use of the wireless camera and receiver. I chose these since low latency was most important factor, and without testing both methods beforehand, a product designed for FPV use seemed more likely to have the smallest delays.

Using a thermosoftening plastic (Similar to Worbla), I created a small box with wrap around tabs on the back and holes for the lens, antenna, mode switch and power connector. The tabs allowed a short loop of steel wire to be attached to the camera module and wrapped around the lip of the head opening.

The wireless camera requires a 3-5v power supply, and on FPV drones this is usually provided directly by the lithium battery pack. I used a standard 18650 cell and holder with wires from the terminals spliced onto the camera's power cables to provide 3.7v input voltage.

Step 4: Receiver & Phone

Since my phone's 5.5" display was slightly too large to use with this headset, I used an old 4.7" android phone. Incidentally, this phone has the older Micro-B connector, removing the need for a Type-C OTG adapter.

There are many apps on the Google Play store designed for this purpose, but the simplest and most reliable I found was the "FPViewer" app. Once the cable is connected between the phone and receiver, and the app recognises the receiver module, you can open the live display and change the view to duplicate the image on both sides of the screen, allowing you to view it up close via the use of FPV goggle lenses.

Step 5: Mounting the FPV Goggles

With the phone centred in the FPV goggles and the focal length and lens separation set, the goggles can be placed inside the head part of the costume. While the universal design of DIY VR goggles tend to be bulky, there was just enough space within the head cavity to wedge them in place.

Where space is more limited, low profile FPV options are available which use their own miniature displays and integrated wireless receivers to shorten the distance to as little as a few centimetres from your eyes.

Since accessibility is limited, it is inconvenient to adjust any settings once it is fixed inside the head space, be it temporarily or permanently, hence the requirement for a long battery life. The use of a digital display and camera for real time viewing is not without its drawbacks, but it's certainly worth considering as an alternative to partially transparent viewing windows.