The case will be split into two parts. The lid will contain a window for viewing the number and a peg to hold the spinner in place. The bottom will have a place for the spinner's peg to rest, something to hold the rack in place securely, and a slot for the rack to slide.
First a box will be defined that will show the space that the lid will occupy, which can be used for both the top and bottom.
Add (Shift + A) a cube. Name it
LidSpaceand change its Location and Dimensions in the Properties (N) sidebar according to the following illustration:
Add (Shift + A) another cube. Name it
LidLipand change its Location and Dimensions accordingly:
Select (right-click) the LidSpace and Boolean union the LidLip to it.
Select (right-click) the BoxExterior, duplicate (Ctrl + D) it and name the duplicate
BoxLid. On the BoxLid add modifiers to Boolean Intersect with the LidSpace and Boolean Difference with the BoxInterior.
To make a window for viewing the numbers, Add (Shift + A) a Cylinder...