How do I insert an item into a block?

There is an idea in the plans (I will try to explain through a translator, if it is not clear, ask, I will try to clarify). There is an empty case as a block, it holds 4 cubes. There are also 2 items - cube 1.0 and cube 2.0. Cube 1.0 brings for example 1 diamond per minute. A 2.0 cube is 2 diamonds per minute. Cubes do not bring anything if they are not in the case. The case also has an interface for collecting diamonds. You can insert it into the case in any order, the main thing is to insert it in the place where the player looked. How can I implement inserting cubes into a block with the right mouse button and also taking out cubes by pressing the shift and right mouse button? There should also be a white border of the place where the player is looking at on the body for further insertion of cubes there, but how to do this? I've been trying to figure it out for 3 weeks, but it still doesn't work out.