If you have trouble sourcing a melt n pour soap supplier, try this cheap alternative made with regular bars of soap. I chose this lux soap because it has mineral salts and marine extracts to make my ocean themed soaps.
Shred the bar into little curls. You can save these for dressing as well.
Then add a little oil or water. Through some experimentation, I realise you need a little oil to protect the soap from drying out & hardening in the microwave. But, not too much or your soaps will be too slippery to manage in the shower.
Then hit the start button on your microwave. Stand back and watch the soap explode, I believe soapers call this the volcano effect in the hot saponification process. Stir down the foam and keep going until everything is melted.
Spoon the liquid mixture into moulds, I use ice trays to make cute little accent soaps. Leave it in the mould for at least 24 hours before popping them out.
After popping out the soap, cover with a tea towel and leave it out to air dry for a week. And you have your fancy guest soaps!