Use the new zModeler 4R7 feature to create the overall shape of the object, beveling it, creasing it and creating the circle opening on top. Use Dynamic Subdivision to assist you in the overall shape and tone of the model. Once you have it where you want it using zModeler and Dynamic subdivision, then click Apply to convert your Dynamic Subdivision to regular sub division. You model’s polycount will ramp up quite a bit with 3 or more sub division levels setting you up for the details. Feel free to add more levels if need be but beware once you get into the millions of polygons it taxes your computer greatly.
Next click PolyF to see all the polygroups. Do control W to make everything one polygroup.
Turn off PolyF
Turn on symmetry so that your brush will affect all four sides of the cube. Probably going to be X using radial symmetry set at 4, but experiment just to make sure.
Next using the mask pen, paint the mask on the sides of your model in the shape of the details you want.
To mask press control key and paint your mask. Hold the alt key while the control key is pressed to erase mistakes or refine. Adjust your brush size accordingly to paint effectively.
Probably be good to sharpen your mask too once your are done with masking all your details.
Once your details are in place go Sub Tool menu and under Split, click Split Unmasked Points. This take all your details and make them into a separate sub tool, separating it from the main model.
At that point you can either delete those details by deleting its sub tool or keep them and just click the eye ball to turn them off.
The separation will give the desired hollowed out effect.
There may be others on the forum that may have better advice with more experience, but I think what I have given you gives you a great start.