You can use most any container as a soap mold as long as: 1. it won't melt from the heat of MP soap being poured into it, 2. you can release your soap from it and 3. it's clean(!). The possibilities are endless and limited only by your creativity and the above. I like silicone and other easy release type soap molds, but I've used a McDonald's coffee cup, fruit cup and pudding cup containers, milk carton, juice can, and even a Pringles container (individual serving) for a soap mold - recycling is cool! I also have silicone ice cube trays in different shapes for embeds - these are easy to find at The Dollar or Goodwill store. If I remember correctly, the Soap Queen even used a PVC pipe for her MP citrus slice soaps a few years back and some CP soapers use PVC pipes too. Sometimes when I go to the store, I can't help but wonder if a container would make a good mold or not.
I've rarely had any scent transfer to a mold unless the FO/EO "ate" at the mold or when the soap was poured in too hot and usually with the cheap soap molds (thin plastic) like you can find in most craft stores or once with a cheap silicone mold I bought online manufactured in Korea. As long as you wash your molds well in warm water after use, scent transfer shouldn't be a problem.
Welcome to soaping - it can be addicting!