Collect rests of used soaps, regardless of the sort, use old domestic gadget and scrub all this.
Step 1: Mixing
Mix this to get uniformly mixture.
Step 2: Soaking
Use a form which is heat resistant. Add water (not to much), just to soak mixture.
Step 3: Melting
Put this in oven:
Adjust temperature to max 100 C°. And let them to melt/heat, until bubbles arrive. With metal stick you can stir and check if all is heated through. About 20-25 minutes total.
Put this in microwave:
Take a steps of 30 sec, constantly monitoring the status, to reach bubbles pop out. With metal stick you can stir and check if all is heated through. About 5 steps....5 minutes total.
Step 4: Cooling
Put this outside, to cool dawn. Form future looks. Wait until is cold and pick it out. Its ready to use.
Step 5: Forming
Or, until is still WARM - not HOT, from with hands future appereance.
Of course, you can experiment as you like!