Draw a diagram or sketch of exactly how you want the desk work station to look and operate. For the old-fashioned way without computers, the view should be clear above the desk. Design the surface with extra room around the place where the mixing board will be. This will depend on how many channels are in the mixing board you intend to use. For a 24-track Tascam mixer, for example, plan on 18 inches by 18 inches for the board, so add another six or more inches all around. In other words, the studio desk would be at least two feet square.
Use wood. Metal may cause vibration and resonance that can affect the mix of music. So hunt for an old desk or table made of real wood. The heavier the better because it will soak up unwanted sounds and vibrations. You buy new as well, but make sure it isn't particle board, wood made from pressed together sawdust. Bolt the mixing board to the surface if it has mountable brackets. Otherwise, build a container for it. In other words, for the Tascam 24-track, build a holder 18 by 18 with three sides: front, left and right. Leave the back open for wiring.
Allow space for the wires and cords that will be attached to the back of the recording mixer. If you do build your desk with shelves, don't put a back on it because this will make it more difficult to troubleshoot connection problems or to change inputs.
Use a table for the studio desk if you have no need for drawers. This will make your workstation cleaner and easier to navigate. You can use a side table for additional equipment such as a keyboard or recorder for playback. For the power supply, it's best to bolt it directly to the table or desk. You can fit it underneath, but it will be more accessible on either side.