The kit contains two weirs in fact, a small one and a large one, and I used the larger one for my layout. The smaller one has no superstructure and would be suitable for a small pond.
Some of the pieces are plastic, some foam board and there are also laser cut cardboard and wooden pieces. One therefore needs a general purpose glue rather than just a styrene glue.
The plastic parts have been 'weathered' by the factory. The process of weathering them however seems to be limited to dumping the parts in some paint! The results are so poor I emailed Faller asking what was wrong with the parts and they replied saying it was factory weathering "as described on the box". Well, the box says nothing of the sort.
The walls of the weir are to be cut from a foam board depicting a wall. Cutting that with a sharp work knife resulted in a tear, so take extra caution with that.
The laser cut wooden and cardboard pieces were easy to separate and clean up
The assembly of the gear mechanism to raise and lower the water barrier needs revision. The parts plain and simply cannot be assembled as instructed in step (b) I had to come up with my own plan, switching parts 1/17 and 1/16. Step (c) instructs to cut a rod to a length of 44.5mm, which turned out to be way too short! At that length the part does not even reach the other side of the model.
It seems that the design of the mechanism has been changed as there are holes that are not used. It is as if the design of this kit was given to a summer intern to design and nobody in managment actually tested assembling this kit!
The water barrier can be positioned up or down over a range of 3mm. Yes, just 3mm difference from the raised position to the lowest position!
Despite all that, I was able to make a decent looking model out of the kit by assembling the barrier like this:
I did not add the railings and glue down the top walkway at this stage.
I could then place it on the layout (before the lake was done)
In order to simulate a good strong stream of water going through, I made some small waves out of Woodland Scenics Water Effects
The upstream side is protected by a barrier of floats which I made up from small beads
I added a path to it, and the waterfall below, to complete the scene.