I have done a youtube video to turn your smartwatch like fitbit versa or galaxy watch active into a 3D hologram with a very simple craft trick.
You will need a card board with both its side of 3cm long & the base to be 4cm long once done use that card board as a stencil to cut out 3 such triangle from any hard transparent plastic. I have used the case for the AA batteries I got from Walmart. You can use acrylic or the glass of a CD case but since the cut outs are tiny it will be hard for you to make a precise cut. Watch the video for more detail.
Once done you need to transfer either the attached images on to your watch or create your own such images either by using Photoshop or Paint. Now align the pyramid in the center of the image & that’s it the hologram will appear.
The above attached images are 100px by 100px, If you recreate your own make sure to use a black background & place the object as I have done in the above images so that you can place the hologram cone in the center. Check this page back again as I will be adding more such images with different objects that you can use for the the 3D hologram.