Create niagra fluid from custom shape (aka fill volume)?

I have been searching all over but no luck so far. What I want seems like it should be simple to do. I just want to have a custom shaped object, it could be a dollar sign, a Z shape, whatever, be filled with niagara fluids. I was able to start with a Niagara 3D pool preset and use a static mesh to emit particles form the TRIANGLES of the mesh, but not the volume. I did find this, but is the right way? Can Niagara emit particles from a mesh volume - #10 by Michael.Galetzka