The sinkers i use are old tire weights. all you need is a vise, hammer<==(always wear safety glasses!), and drill+ bits. this process is much safer than melting! First smash the spring steel down using hammer and solid surface. then smash one end of lead so it is half as thick as the rest. Place this flat end up in vise ,drill small hole for threading line. then use a much larger bit to bevel edges of hole. make sure hole is free of rough edges and or burrs! easy and free,see pics below.