How To Make Your Own Mold
You will need: Plaster of paris
                           A 1 quart bucket
                     A razor knife
                                               Package of clay shaping tools
                                                             Sand paper (coarse, medium and fine)
                                    A pair of old stockings

To make a pair of lasts (foot mold), take a pair of your old pumps or go to a second hand store (goodwill etc.) and buy a pair good new like pumps.  Make sure they fit your feet.
Next, buy a jar of vaseline if you don't already have a jar.
Apply some vaseline on your (3) fingers (index, middle and ring finger) and apply all inside and around the shoe.  Make sure you got every inch of the inside.
Next, mix in your bucket, the plaster of paris.  Put/pour about cups of plaster of paris into your bucket.  Mix in two cups of water and then a little water as you mix.  Mix it to a creamy runny consistency and pour into one of the pumps.  Make sure the the substance is more liquid than solid.
Next, mix and pour for the second pump.
Let shoes dry over night.
Now it's time to remove the lasts.  Cut the center of the pump from top front vamp down to the toe/soles and from the top back heel down to the insole.  Split the shoe open and bend the heel/back of the heel downward while lifting the mold/lasts upward and out of the pumps.
Next, after letting the lasts dry overnight let them dry another day.  Next take one of the clay shaping tools (wood stick with steel tri-angle shaper on one end) and scrape the flat outter edges of the bottom of the mold making the edges more round getting rid of the sharp edges.  Now take the coarse sand paper and sand the edges and the rest of the lasts.  After sanding the lasts with the fine sand paper put the lasts into the stocking and tie a knot to keep the lasts in tact.
Your lasts are ready to make your shoes.