We took the used Expedit apart and basically cut each piece on a circular saw at my dads and bought a big bag of pegs (you'll need twice as much for the two halves) to fix all the 30 vertical boards.
As in our particular case, the full 370 cm width would block the entry door, so we needed to make is shorter. But removing a single column would make it asymmetric where as removing two columns would make it to short. After a while, we achieved symmetry with the 9 columns by removing one from box halves but putting one back in between them.
See the pictures... :)