You could do that, but I really don't recommend it. If you were to go this route, you probably should use fiberglass cloth and matte and fiberglassing resin (from Home Depot or Lowes). Unless you're using a coarse paper it probably won't take resin too well, and you might as well use fiberglass because it will be much stronger and you won't have to do as many layers. As for the slow curing resin, that will only cause you problems for a project like this. Gravity would be working against you and it would make things much harder for you. If you pour the resin in small batches you won't waste much and it cures fast enough (if you mix it right) that it shouldn't take too long to do. The down side to doing it this way is that you won't have any surface details and the shape will change slightly as you build up.