This is not strictly a Home Assistant guide or project. But tablet wall mounts are surely a topic that will sooner or later be of concern for most HA users. I looked for good solutions for quite some time. And I took several detours with questionable decorative value, before I came up with the way that I present to you here.
This mount consists of magnets that framelessly hold a tablet in place about 12mm away from the wall. The whole fixture is invisibly hidden behind the tablet. You can fully detach and reattach the tablet at any time. When attached the magnets hold it in place very firmly. Plastic buffers ensure that the magnets do not snap hard onto each other and break. The convex buffers also make sure that the tablet slides perfectly into place when you attach it.
The final result is light weight and visually appealing.
How this is built
This is a project description but also a guide to build your own.
So let me show you how the whole thing is created.
Here are the parts that you need for the mount itself:
On the left side are the magnets. These are strong Neodymium magnets, 30 mm across and 5 mm thick. They have conical center holes for countersunk screws. You need 3 of these with South pole facing towards the screw head and 3 with North pole up.
These magnets are really strong, especially when used in pairs. You could actually even buy a somewhat smaller diameter.
Below is how each magnet assembly looks. In the second image you can see how the little white plastic screw cap separates the two magnets. This prevents the magnets from breaking when forcefully clicking onto each other and it also perfectly centers the magnets as the convex cap settles into the empty conical hole of the tablet side magnet.
The distance of the drill holes in the wall depends on your tablet size. I used a cheap Fire HD 10, which works very well for over a year now (constantly on power with the battery not inflating). My holes for the Fire are 19 cm horizontally apart and 10 cm vertically.
Take care not to hit any cables of your power supply in the wall when you drill. This is the reason why my junction box is placed out of center of the tablet.
Attention!
Many tablets (including the Fire) have a built in magnet sensor to switch their display off when they are placed in a closed cover. Test your magnet positions and polarities on the tablet BEFORE you drill the holes into the wall. Otherwise your tablet may go dark forever when you later glue the magnets onto it.
After you screwed the three magnets in place, put their counterparts on top of them. At this point we do not yet use the plastic caps between them. This is to make sure that the outer magnets are lying perfectly flat when we glue the tablet onto them.
Now place your tablet on the magnets and center it in all directions. Align it horizonally with a water level and drive in two small steel nails below it to temporarily hold it in place.
Measure the exact distances of the magnets from all sides, take the tablet off the wall and mark the magnet positions on the backside of the tablet.
Fill the marked areas with a patch of epoxy glue.
Let the glue rest until it begins to thicken. When it just starts to lose its honeylike consistency, place it on the nails and carefully push it against the magnets.
When the glue has cured, carefully detach the tablet again, now together with the three glued on magnets. If a bit of glue has entered through the center holes it is possible that it has reached the screw heads. If this happens, try to drive a sharp cutter blade into the gap between the magnets to break them apart. To avoid this risk, place a sheet of cling wrap between the front and rear magnets before glueing.
Unfortunately with one of my tablets I used a bit too much glue and I did not wait long enough for it to thicken. Below you see a good result and a not so good one. You may want to learn from my mistake.
Now place the plastic screw caps on the screws. I fixed them with a bit of normal glue.
For the power supply I used an angled high quality USB cable that I cut in half.
Now it’s time to finally click the tablet to the wall. If you did everything right, the magnets will snap nicely onto each other without a hard metallic sound while the plastic caps act as buffers and centering aids.
Et voilĂ . Nice job.
Enjoy your elegant new mount! 
