Tablet Storage With Flat Bottom

When I printed the part the bottom was rough due to the feet on the corners and thus requiring support of the whole bottom part, I also used tree supports printed touching the build plate and they stuck to the walls of the circles making these slightly rough, I would suggest that you place the supports yourself so they are not touching the walls of the holes.
I have made the bottom flat so it prints smooth, I may further remix this so that no supports are needed at all