Simple; make a 2 peice mold.
Pour some your molding agent into the mold box until the box is 1/2 full. Press whatever it is your molding into the agent until it is embedded 1/2 way. Allow the molding agent to cure. Apply a layer of release agent to all of the exposed molding agent in the mold box and to the insides of the mold box, but do NOT apply any to the object being molded. Fill the rest of the mold box with molding agent and allow to cure.
Turn the mold box upside down to remove the tope 1/2 of the mold. You may have to tap it a bit. Remove the molded object from which ever 1/2 of the mold it stuck to. Drill 2 holes into the top 1/2 of the mold. One at each end of the impression of the object that was molded. One of these you'll use to pour material into the mold, the other is a vent to let out air. If the molded object had a complex shape you may need more than one vent.
Put the top of the mold back into the mold box and start pouring.
What to use for a molding agent and the release agent depends on the material that will be poured into the mold. For soft plastic lures plaster of paris and vaseline work well.
Pour some your molding agent into the mold box until the box is 1/2 full. Press whatever it is your molding into the agent until it is embedded 1/2 way. Allow the molding agent to cure. Apply a layer of release agent to all of the exposed molding agent in the mold box and to the insides of the mold box, but do NOT apply any to the object being molded. Fill the rest of the mold box with molding agent and allow to cure.
Turn the mold box upside down to remove the tope 1/2 of the mold. You may have to tap it a bit. Remove the molded object from which ever 1/2 of the mold it stuck to. Drill 2 holes into the top 1/2 of the mold. One at each end of the impression of the object that was molded. One of these you'll use to pour material into the mold, the other is a vent to let out air. If the molded object had a complex shape you may need more than one vent.
Put the top of the mold back into the mold box and start pouring.
What to use for a molding agent and the release agent depends on the material that will be poured into the mold. For soft plastic lures plaster of paris and vaseline work well.