I have just made a little video on how to make a bangle mould. These kinds of moulds which are called a variety of names from a one part mould to an open mould are by far the simplest moulds to make. I have used an RTV silicone to make it. RTV stands for Room Temperature Vulcanising which in plain terms just means that the silicone will cure at room temperature, it doesn't require any additional heat to cure. You just add a catalyst which comes with the silicone, mix in well and pour.
So, now that I have shown you how easy it is to make a bangle mould you probably want to know how to cast resin into it. Go click on the link for my e-book Schmook Books > Resin : Jewellery on the right hand side of my blog or here to get all the information you will need and more.
You can use this technique to make moulds for anything that has a flat base and no major undercuts. Undercuts are features on a master pattern that prevents the piece to be removed straight out of a mould easily. When you have undercuts you will need to make a more complicated 2 or even 3 part mould which is a whole other kettle of fish. I might show you how to do that one day, but until then, go and have some fun with this one!