I saw a NE3 otoscope for ear inspection on ebay for under £10.00 - decided to get one and try to set it up as a nozzle camera on my Neptune 4 - images are OK considering the price.
I made a clip on camera holder to try it out. the clip fits nicely to the front of the print head but as it stands the camera can't get a view of the nozzle.
I removed the silicone rubber nozzle cover a while back - more trouble than it was worth.
Needs work - removal of print head base plate - done - and works well - I would upload a video but Thingiverse does not appear to support direct upload of clips.

I have reworked the thing twice - hence uploaded mk3 version which when printed in PETG fits perfectly on my machine - however the angle of the hole is a bit shallow so I had to do a bit of filing and used a couple of lines of hot glue for the camera barrel to rest against and maintain a good angle. I will do a mk 4 to address any issues

ELEGOO

ELEGOO NEPTUNE

No

Yes

0.2

100

My prototype is in PLA but a PETG version might be better when I iron out the camera mounting issues

I had to hand hold the camera in a suitable position because the clip as it stands can't get the camera close enough

I removed the bottom cover from the print head held on by 6 screws - it seems to only be there to hold the model light in place. The camera has its own led lights so the model light is redundant and easily disconnected. The led cable needs securing, can't have it flapping around during a print.
The tablet shows the real time view of the nozzle and is connected to the camera by wifi.
It looks OK as it is now but could be moved a little closer for a more in focus image.

• work in progress.
  Tried it during an initial set Z and it works very well but could do with being a few millimeters closer to the nozzle

I fixed some issues with mk3 - camera is now possible to get really close to the nozzle - the thing now prints without supports with the largest flat side on the bed.
I had to make the hole a little wider - the camera can now be positioned for best focus and size - once achieved it can be glued to the thing to make it a clip on camera set to the correct distance.
After set up, I tried printing a 35mm test square of 0.2mm height - 1 layer - with a skirt of 2 lines
It works really good and allows the shape of the extruded filament to be seen (flattened, round or just right) during the skirt printing - once the printer kicked off at 150mm/s the nozzle remained sharp but the test square surface was blurred by the motion.
Printing 3 skirt lines would allow more time to adjust the filament shape with up or down Z movements.