I definitely re-purpose molds - from anything and everything I can think to try! Of course I have a huge mold collection with all sorts of things, lots of various candy and resin molds in my collection now. But I still always keep an eye out for little plastic packaging items on everyday household items that could make a good mold. You'd be surprised at how many places you'll find them! These cheap molds are often times only good for one-use, but it's great to have something new and different. It's also a great way to add new flair to molds you use often by embedding new shapes inside. Some great ones to try are the plastic trays that you'll find holding cookies and candies (often times in boxes or tins of goodies!) Also you can cut the side of a paper milk carton off and modify and comform the sides right into a quicky little loaf mold! Plastic packaging that your food comes in is another great way to find free mold possibilities in a variety of different shapes.
It's a wonderful way to get creative with your soap making adventures, and it feels good to be able to re-purpose some of this stuff that would otherwise just be useless garbage! I still do it and I have BOXES of molds... then again I'm a total mold addict so maybe it's just me, LOL!