To finish it , you can use porcelain tile, gresite or liner, that can be welded and adapts to the measure and has great tightness.
If you plan to place the pool on a roof of a bloc keep in mind that the neighbors may have much to say about it:
With regards to loading we may assume that we have to put structural reinforcement, with the inconvenience that we have to obtain approval from the community of owners.
It is also important to take into account that the owner who owns the pool is responsible for the effects that this may cause to other neighbors, so you should expand the coverage of your home insurance.
In addition, you must always ask for permission to work, which varies according to the town hall, and consult about urban heritage issues; For example, in some districts this type of action is limited. Without going into materials, specific typologies etc, for a minimum pool of about 3×3 m and 80 cm deep you have to start from € 10,000-15,000. The main difference in price with respect to a swimming pool on the ground is above all, due to the reinforcements to be made and other conditions.
The final price will depend a lot on the materials, the type of machinery filtering , or whether or not lighting is added.