Health and Safety
RepRap works with materials at temperatures from ambient to about 240 C. Clearly at the top of this range you are in danger of burning yourself - be careful! Also some parts of the RepRap machine (particularly the extruder) are capable of generating quite high forces and torques - don't get your fingers in them.
Please be careful and use a double boiler when melting wax or thermoplastic. A double boiler is a set of two pans. The lower pan contains hot water, and the upper pan is placed in the lower pan. If you do not have a double boiler, put your wax or thermoplastic in a soup can and place that in a saucepan half full of water. Place the saucepan on your stovetop or hot plate and heat normally.
Every manufacturing technology that humanity has ever come up with has been used to make weapons, and doubtless RepRap will be no exception. There is no absolute way to stop this, any more than one could stop someone buying a second-hand lathe on eBay and using that to turn up all sorts of very nasty objects. However, the RepRap researchers will work actively to inhibit and to subvert the use of RepRap for weapons production, whether by individuals, companies, or governments. And we will remove any such designs from this site. At least RepRap is not very suited to weapons manufacture - it tends to work with more subtle and delicate materials. Give people an internal combustion engine and a few will make tanks; but many more will make ambulances.
