This is a project I made while on Holiday for Christmas, it took about 20 hours and was cheep if you can find the supplies at a second hand store.
It is fully functional and works with infra-red quite well, the iris lens cover was a left over from a pair of goggles that were never finished their construction is much the same as found in my steampunk goggle instructable.https://www.instructables.com/id/Steampunk-Goggles-Iris-with-interchangable-lenses/
Step 1: The Electronics
This will be a bit tricky if you have no electronics expierence, the Periscope has two basic components, the camera, and the picture tube.
The tube assembly is off an unkown brand of cam corder monitor, it was lose on the shelf and I bought it for a buck.
You most likely will need to purchase the entire camera, (cam corder) and remove the monitor, usally the recorder breaks leaving you with a lens and monitor, if your skill level is up there you may be able to remove the video camera and monitor from the same unit.
I was not lucky enough to find one whole.
Usally the camera power input wire is labled on the board, in this case it was 12 volts DC, most of the other wires will be of no use to you,
they will be for different exposure modes, switching the zoom, ect.
The most important thing to know is the voltage needed, and which wires are for this purpose, input and out put signals are very low voltage and incorrectly connecting them will not likely cause a board failure, if however you hook up 12 V to a video out wire you may have just ruined that board. ( I apologize I can't offer a more conclusive way to determine the exact wire of choice, I only know the one I found by the deduction.)
I saw a small 12+ marking on the back of the monitor board and hooked it up, in about 5 seconds the monitor began to glow.
The ground wire generally goes to several places on the board, while signal and command wires go to a single point on the board.
All you need are 4 wires, ground, 12v positive, video, and sync.
If your monitor board has wires from a zoom and other lens functions they can be clipped, these wires are just routed through the board and do not effect monitor use, often times they are a different gauge, plus you can see they are hooked to switches.
Once I got the tube to glow, I just tried the input wires from the camera to different ones on the monitor board until I got a picture, be sure to tape the 12v wire so you don't accidently touch it with a signal wire.
In the pic you can see the red, black, blue, and white wires from the lens command switches all clipped off.
This only left 4 wires the 12v was labled and the ground was "obvious" only two to choose from for my video input,
Fortunately the camera I found was still in the box so the wiring was very easy, resist the urge to think that you can hook up the wires from the different components color for color, yellow was 12v on the monitor, while from the camera box you can see red was the 12v supply wire.