Firstly may I say that I am not the worlds best at decribing all the things you may want or need to be able to make your own transit box, but I have done my best to help all those who are interested in 34 diy. I have also taken a series of pictures which may help you in deciding where to put what and how in you box. Being only able to list a few pictures on the forum I have them on file and those who want them can email me for them directly at mailto:firstname.lastname@example.org
So the basic sizes I thought you would need are length 121cm, width 28cm, hight 26cm. The wood looks to be 18mm thick approx.
The front, bottom, lid and back of the box are single pieces of wood. Each corner has the end cut off. The end panels are made up of one piece of wood with seperate pieces added to form an outer square making a recess for the carry handle.The outer square pieces are 55mm wide by 18mm. The ends are 38mm thick approx.
The inner measurements of the box are 25cm x 22.5cm x 113cm.
The hinges are 21cm in from the end the two strips of 55mm wood that run along the lid and the base are 7cm in from the end of the box.
I am sorry to put these details in such a confusing way but I have tried my best for you...I hope you can make something from them.
All the best,