The main concept of the design is "Easy to modify".
You can insert a variety of blocks as you wish to drive your design. You can make the box to any size. You don't have to drill the box to insert wires, and you can insert another piece of the block if you don't want the hole anymore. If you want to re-design, you don't have to find another box, but you can use these blocks for your new design.
These blocks are available with a 20 x 20 mm Aluminium Profile and M3 nuts-screws.