The magnets are held on to the tweeter hole in th MDF plate by their own magnetic force, and the fact that you have long strips of metal plates covering the sides of the hole (don't you....???!!), thus the north pole of the magnets are on one side and the other side holds the south pole magnets. This is done so the top row of magnets on the woofer section of that speaker must have the same polarity as the row of magnets in the tweeter section closest to the woofer section (sounds wierd but it's simple, don't worry on what exactly is the N and the S polarity, just assume that one is the N and the other is the S and work consequently out of that assumption. When this is done, you are thus sure that the speakers are working in fase.
The magnets are arranged as shown in the figure. In my case, as in the danish original project, two magnets are placed ontop of each other to generate a stronger magnetic field. The distance between the magnets on the same side is obvious, because they will not stay any closer than they want to (their magnetic field wants to).
The personal dimensions involved will depend on the material you use, just make the distances such as to have a 1 mm. distance between the tweeter membrane and the magnets, on each side.

This diagramme shows the returning conductors made out of the aluminium material , I chose to use wires and make the tweeter conductors not as wide as the original project. You experiment and find out.

A list of materials needed.

The construction recipe