3d design desktop organizer

I Have made a custom desktop organizer. It can hold any type of pencil or pen ect. The dimensions for the desktop organizer are 137.56 mm L, 101 mm W and 124 mm in height. On the back of the desktopotganizer thereis a spottohold a calculatorofant kind. When you go around to the front of the organizer there is a spot to hold any type of smartphone including Iphone, Samsung ect. An issue I came up against was getting the correct sizes for the calculator and the phone. If I could redesign this again I would make it smaller and more compact. 3D printing my design will help me because everything will be connected.