There is a really quick way to hollow out a part in SolidWorks that you may not be aware existed. Most are familiar with the Shell command where you can remove a face or faces and shell the rest of the part. However what most don’t realize is picking a face to remove is optional. If you define a shell thickness but do not select a face to remove it will still shell, or hollow out, your part to a specific wall thickness.
Of course, remember eventually you still need to manufacture the part.