Jan thought about making the first castle tower of the Kessel castle (called Keverberg) in the south-easter part of the Netherlands were we live of which a picture is underneath of around 1100.
As only parts of the lowest part of the tower was found no one knows for sure how it really looked and by a second glance it looks a little bit dull. So he looked further for some more examples of early castles/donjons or something else. These were found:
Motte Lütjenburg in Germany
Bachritterburg Germany
Herne Germany
reconstruction motte Eindhoven
So it was decided to build one himself without knowing how; just knowing that it would be partly stone and partly wood. As it wasn't know how it would be used; eg for skirmish game (so figures had to be put inside or just as decoration on the side), building started out of mostly balsa wood and a base of polystereen on a plastic base and by try and error it became this.
A, yet unpainted, figure just for letting see the scale on the second picture on the left
Of course the wooden part plus the roof comes off; it has three detachable floors and some shooting slits in the stone basement. This can be seen by the two pictures underneath.
This is the first part as the tower will become part of some sort of a motte and bailey casttle but that will be part two.