Hello Happy Crafter-
Nice to see you here.
I encourage you to try a vessel, they can be fun, and interesting to play with.
I would suggest starting small-
the smaller it is-the easier it is to handle for a first project.
As for fibre- Merino wool is the best way to go. You can try other soft fibres, like corriedale or moorit. But the basic Merino wool is always a good way to go, as it is soft and the hair thin enough that it takes little effort to felt them.
If you were to try using Romney, for example (coarser wool- better for needle felting) it would felt eventually, but would take AGES to get to that point.
The finer the wool - the better.
With Merino, you can also experiment with mixing other fibres on the surface, as Merino 'grabs' those fibres easier. Such as silk, tencel, wensleydale or mohair curls, soy silk, yarns, you name it. Wet Felting a Vessel- is a great time to experiement and enjoy yourself. Besides- I think you've got to be in a pretty good mood to felt something on a bouncy slippery water-filled balloon. lol.
please feel free to post here or pm me if you nedd any help. And Have fun!!!!!