I finally got some time to apply the MDF layers to the battery terminal covers.
And it was very satisfying to know that it was a very nice fit. The only exception was of a couple of extra centimeters in width, which were promptly cut away easily.
The entire cover is made of three MDF layers. The first two are 10mm thick whereas the last one is 5mm thick.
Even the space for the bus bars is pretty much spot on. I just need to make some manual cuts (and special bus bar) for the first two modules, which have the same polarity.
The third and last layer is a 5mm MDF cover:
All the layers are fixed using simple wood screws: