Mold for making small concrete sinkers, around 15g. Use rubber bands to hold both pieces together. I used 1:1:1 ratio of cement, sand and water. Spread some soapy water in the inner face of the mold so it doesn't stick. Place a wire loop in the bottom end, close and pour the mix. After one day, you can take them apart, but it still needs drying. They are fragile, but really cheap to make. The third model has space to put a piece of 1mm wire to make a "sputnik" style, but it needs testing.