Continuity Camera mount for Dell P3421W, tested with iPhone 11 Pro Max and iPhone 12. Tilted a bit downwards so that Center stage isn't required to get a decent viewing angle as the monitor is pretty thick in the middle.

It also includes a cable holder in case you want to keep a cable there to be able to easily access it and charge the phone while in use.

I'd recommend printing it in PETG as it will be less brittle than PLA, but really any material should do.

Custom sizes:

If the model doesn't quite fit your iPhone, or your monitor, but the overall shape is good you can use “cut” feature in Prusa Slicer to cut the model and increase iPhone or monitor mount width like this:

Both the part that goes on the monitor and the part that holds the iPhone has enough space to cut it cleanly. Then you can resize the middle part (green in the screenshot) to your desired size before moving the parts all together - for proper printing make sure all 3 parts are merged together (see screenshot part list on the right).

Here's a step-by-step guide on how to do it:

Use the “Place on face” tool to put the flat part, the back of the iPhone holder, on the surface

Use the cut tool to cut the middle of the surface close to the bottom, but without it affecting any other walls or features other than the one highlighted.

Perform the cut, and do the same thing again on the larger of the two pieces, this time cutting closer to the top like in the screenshot.

Once there are 3 pieces merge them all together so that they can be moved in the slicer.

Align the pieces. Since they're merged they can be moved without all of them needing to touch the print surface. You can copy the same coordinates for one axis or just move them around by hand until they all align.

At this point you can either shrink, or even remove, the middle part, if your iPhone is too slim for the mount or increase its Z height if you need a bit more space. I'm just gonna show how to increase it, but I think by now the process for the opposite is also clear.

Increase the height as much as you need.

Use the tool “place on face” from the first step to put the part back in the correct

Check your first layer! In case the parts aren't quite aligned you may not get a good first layer which may cause the print to fail. There is an easy fix for this though, just lower the print to actually go a bit below the print surface, since the print is same all the way through this doesn't cause any issues.

Done. All the parts are printed as one (because we merged them).

Hint: If you're unsure about the dimensions, print just a few mm and try it out, you don't need to print the whole thing

Same principle as above can be applied to the part that goes on the monitor itself, it's the same procedure.