The Logitech C905 camera has several advantages for use on a Neptune 4. It is available as used at very low cost on sites like eBay (I've seen it for $8 shipped to within USA). It is very narrow in width so that it doesn't interfere with cables or the bang into the user control screen of the Neptune 4 or 4Pro. Its lower resolution (720p) has zero loss of image quality unless you are watching on a 60 inch TV, but will occupy lower streaming bandwidth so frame rate may be higher, particularly if you monitor via a wifi adaptor. It is extremely easy to configure for Neptune 4 and connect to its USB.
This mount sits on the right side of the nozzle, hanging off the x-axis bar and just above the nozzle (or lower if you want, with some other variations included here). It mounts with two #8, #6, or M4 screws. The webcam isn't screwed on, but slides between two horizontal bars, with an indentation on the back for its cable, so it can go on or off very quickly.
There are also some (optional) cable clamps which can be used if you feel you need to keep the camera position more firmly mounted. One has a strain relief ridge inside, the other doesn't. The main holder has two holes that can be used to attach the cable clamps, you can use #6 or M4 screws and nuts, or you can run an 8-32 (or M4) tap on the holes for those sizes.
I originally mounted mine with the “default” holder, but tried also with the ones that held the camera a little lower. I ended up back with the default because the lower ones made it difficult to see the printed lines being laid down on the first layer, which is one of the main things I wanted a webcam on a printer to provide. For all the versions here the nozzle on a Neptune 4 with be visible the entire time you are printing, which is great for monitoring.
I've included two photos showing the view of the nozzle at the first layer, as well as from a higher view of a finished print (of the cable clamp).
The author remixed this model.
This was inspired (but redesigned from scratch) by Pegoku's camera mount for higher res webcams. I changed the way the camera attaches for the C905 camera.