As mentioned in the introduction, this is an adult hobby. Younger persons are certainly capable of handling the tasks involved but should be under the supervision of an adult.
Some of the necessary materials involve slight hazards. The petroleum distillates used as a thinner for petroleum jelly, such as some paint thinners and removers, are flammable and combustible. It makes sense to keep them away from heat sources such as your melting stove and molten metal. Use them in a well ventilated area.
You will be using a heat source of some kind to heat low-melting-point solder in a ladle to around 400 degrees F. There exists the possibility of burns to yourself and/or the surrounding area... Do your casting on a non-flammable surface. Wear safety glasses and leather gloves. Again, a well ventilated area is necessary due to fuel and molten metal fumes.
Also, READ THE LABELS on everything! Be familiar with what you are using and heed the manufacturer's warnings and precautions. Handle all items properly and use a lot of common sense. Make your hobby a safe one!
(Introduction) , (The Model), (Table of Contents)