The yellow ring is just a finished sample for picture purposes, not included with mold.
They may be a little tricky to begin with but I think they will be well worth the effort. The silicone molds are made from a tin silicone that has a long shelf life and tough enough for many pulls. The molds are handmade by me.
Fill the bottom half rolling the resin around to avoid trapping any air bubbles. You may want to wrap with a rubber band to close the slit in the plug a little more. You will need this slit to remove the ring from the mold. Set aside and let cure to a gel stage. You will have a little bit of flashing from the slit when you remove the casting that can be easily snapped off.The top bubble part of the mold can be filled in layers and embedded with goodies.
Once the top and bottom have reached the gel stage apply a small amount of resin to the castings and join the two halves.
Or you can rubberband together and pour resin in the pour holes which is a little more advanced technique. Take the casting out of the mold once it has started to harden as this will produce a shiner casting if it doesn't touch anything while finishing to cure.
Use dish soap and water to clean your molds. Use rubbing alcohol to remove fingerprints and such. Mix and pour the casting material according to manufacturer's instructions. After the cast has hardened completely, slowly peel the mold from the cast. Work around all the edges before pulling up the middle sections. After a cast is made, be sure to thoroughly clean the mold ( removing any casting residue or release agent) before storing. Store silicone molds in a clean, dry location, embed a rigid mother mold cast if possible to hold the molds shape. This prevents the mold from distorting or warping over time.