![Image](https://www.imgurupload.com/uploads/20201110/2513c966db69167181349798b2b79d2e40a932fc.jpg)
You can't see the down firing drivers (two of them). Amongst that are two 30 cm cubes (26 cm3 internally) which are totally separate. I am going to create the two enclosed sides of the upper and lower slots / gaps with solid wood or stacked L pieces of baltic birch although that may be too expensive. What ever I make that part with there will be a continuous sheet of Baltic Birch ply for the front, back and two sides so It won't be seen especially as I will be putting a grille in the gaps.