The first project is a horn with the well known Fostex FE 103 - here is the old version without E or Sigma.

The folding is an old Isophon plan only adapted to the new driver. One can easily change a horn design by adapting the horn mouth area. It should be between 50 and 70% of the drivers area, in this case just change the original plan to 14cm inner width.

Here is the original Isophon drawing