Try searching the community for “wall mounted tablet” and you will find many threads about the topic. One community memeber (@73roderick) has shared his very beautifully executed project here:
I would just caution you on one aspect… gear such as a tablet has a very limited life so the more the mounting is custom the more you might have to rework it when you want to upgrade it. This is the main reason I have not mounted anything yet. I am tempted to get a touch screen and use an Odroid, or some other SBC, to power it so that I can more easily upgrade the computing part while leaving the display the same. This should preserve my install for a longer period of time but the trouble is that the resolution of these screens tends to be quite lower than the tablets I would consider mounting. Resolution matters to me because I have many multi megapixel IP cameras around my house and would like to view the feeds at higher than 1080 resolutions.