That cup/fan drill attachment is the old school version of making webs. basically, the web-fluid is a rubber cement that sprays out in a fairly wide pattern. The pro is that they look nice, but you should dust them with a powder or fuller's earth to make them more opaque & less sticky. the con is that the fluid is harder to deal with than a hot glue version. It can spill out of the can easily, because it has a thin gap at the lid where it sprays out, so you have to be aware of that while using. the fluid is also solvent based, flammable & has a strong odor before it dries.
The pros of a hot glue gun are that is it easier to use, gives about the same, if not better web effect and is no odor.
The cons are that you can get a serious burn from the gun or hot glue if you are not careful applying these.
ALWAYS wear protective gear, long sleeves, gloves & goggles when webbing.