What does the Mann Co. Painting set do? Is it like normal paint? Does it allow paint to be changed on hats?
The Mann Co. Painting Set is like a Mann Co. Mystery Box.
It can be 'unboxed' and will give you 3 random paint colors when you unbox it.
It is exactly like normal paint. There is no difference between "paints from painting set" and "normal paint".
If you wish to see a demonstration, here is a link.
A discussion can be found here.