+x Warren (Staff) - 1/5/2018 5:19:20 PMHI,You are correct that you will want a silicone mould to start with which you can then pour the casting resin. For clear casting you will want an Addition (platinum) cure silicone as they are moisture free which is essential with Water clear resins as they are generally moisture sensitive. For ease of use, you would want to look at a Water Clear Polyester. They do not need to be degassed in most cases. Tackiness is an issue for resin open to air but its easily sanded off and polished back up. Our polyester will cast up to 75mm thick layers so larger objects are able to be done in one go or with minimal layers.For a rounded bottom or any full 3D object, you would have a totally closed mould but with vent holes and a pour hole. This means the air can escape.. Afterwards you can cut off the vent sprue and use some sanding and polish to leave no trace of the vent on the part.