Hereby a Phone or Tablet Stand, that can be customized to any size.
It may also be used as a stand for things like pictures, books, etc...
Open it in Thingiverse Customizer and build the one that fits to you.
Still Fine Tuning, so please let me have your comments...
Rotate it 90º to avoid supports.
If you print it as shown, then you'll need to add supports anywhere,