Staryberry,

1/2 of each container to mix is enough for 1/2 a bottle. So you can technically get 2 molds out of the box w/the 2 containers in it. You do have to work with it fast, but honestly it's not as bad as it seems. I mixed them in about 45 sec which gave me about 2 min. to mold, and you really don't need that much, just wrap it around the neck and cap and 1/2 way down the bottle. Make sure you have no gaps or small holes and I rolled my bottle on the table to smooth out the outside of the mold a bit before I hit the 3 min. zone.
If you do it my way with the slit down the side, you want to make sure that your mold isn't too thin, because the thinner it is the more likely it is to buckle on you when you pour the sugar in it. I also waited about 1 min after the sugar was ready which firmed up just enough for it not to seep through the slit (but don't wait to long because it won't come out of your bowl).
HTH