Since each build most likely will be different, giving exact building directions makes no sense. I will describe the most important steps during the build, however you will have to use to use own imagination and creativity.

Put all your components on a pile.

Find a suitable cardboard box.

Lay out the components, paying attention to space taken by plugs and connecting cables.

Using a thin screwdriver punch holes in the box through mounting holes on the boards. For each mounting hole punch another hole just outside of the outline of the component, so you can make a small loop. For components that will be wrapped by the zip-ties, punch holes on opposite sides of the component.

Tie the components to the box. The loops should be tight enough to secure the part, but not too much, to not to break it.

You may have to use washers for connectors. Even though they may look secure after screwing on the holding nut, they will become loose very quickly. If you don't have big wasters, use piece of metal from a can.

For USB connectors mounted flat on a side, add one or two layers if cardboard underneath to rise it. Otherwise you may have problems connecting thicker devices (like flash drive or wifi stick).