Custom built cabinetry is one of the most popular kinds of bespoke carpentry work that is ever ordered, right after rooftop and stairs. While there are many people who prefer to make their own cabinets, the absolute and honest to god truth of the matter is that there is nothing that even comes close to the kind of flexibility and storage space, not to mention the build quality of the whole project. One of the most important things that you can do when it comes to giving the instructions for the bespoke construction of a cabinet is to have the carpenter who is going to be working on come over and take a look at all that you need them to do. Show them the place where you plan on putting the cabinet, ask for their view on the design, tell them what you plan on using the cabinet for and then once again let them know what all will go where. They can thus suggest improvements to the design that you have proposed and while they are there, they can go ahead and take the measurements of the whole place so that they know exactly what to build and how big to build it.
I can suggest a number of uses and locations that you could think of getting a custom cabinet built for. I would personally get one built for my television and speaker setup where I would put up nothing but the best of the consoles and get some additional wood work done to conceal all the wiring. If possible, I’d get the cabinet designed in such a way that I could use my consoles without having to rummage through the drawers of the cabinet. Something like this would possibly be accomplished using smoked glass I would assume.