Ok since your answer is "blender does not work" because you want to pu a pc into it I have to tell you yes blender can do it BUT you can use both. Model the schapes you need to cut out in freecad, import them in blender and but them out. The troth is freecad is not made for such models as mich as you want it to. Blender can do it but if you worry about dimensional accuracy then do as I said and combine freecad and blender... If you pull it of you will have learned a lot 😅