I used a salt and pepper application. I used a small squeeze bottle of the acrylic powder and an eyedropper for the monomer liquid. blow a little powder onto the mold using the squeeze bottle and than apply a little monomer over the same spot, I would keep doing that all around the mold until I built up a thick enough wall to be rigid and strong. I stopped making shells that way because they ended up with very thick walls and not as much space left on the inside for drivers as I would like and because the monomer is none to good for your health and It was making me feel a bit ill.
It looks like your shell is a bit rough around the edges. I recommend sanding that down until it is nice and smooth before putting it in your ear. I have scratched the inside if my ear before and it is not fun.