If you are new to resin casting then check out this detailed article on Basic resin casting over at our sister site.
The basic materials you need will be Resin of course. I highly recommend starting out with a craft resin and then as you progress you can purchase in larger quantities. This is the same resin that can be used for resin-pouring projects too.
Techniques to Embed Flowers in Resin : 12 Steps (with Pictures)
How to Make Real Flower Resin Jewelry
DIY: How To Make Resin Crystals With Dried Flowers
How to Make Botanical Jewelry and Bookmarks with Pressed Flowers and Resin
Polyester Resin: is a liquid plastic that hardens when a few drops of the catalyst are added to create a chemical reaction. Polyester Resin is durable and is the resin of choice for industrial applications and serious crafters who are experienced in resin casting. This resin is highly toxic and should be used in a well-ventilated area using protective masks to avoid inhalation. One main advantage of Polyester Resin is the depth in which it can be poured for larger embed projects. Polyester Resin is cheaper to buy than Epoxy resin as it is generally purchased in larger quantities such as 1lt + tins.
Epoxy Resin: These resins are more frequently used in the crafting and hobby world, they are easy to use with a low toxicity, making them suitable for ventilated craft rooms and work areas. Epoxy resin is perfect for jewelry casting as it has a shallow setting depth, so it will cure quickly when used correctly.
For complete instructions on casting with resin read these Basic resin casting techniques
Here are our favorite supplies for using resin when casting
Casting Resin
Measuring Tools
Disposable Mixing bowl or cup
Disposable tools
Suitable resin molds
Spray oil Cooking Spray
Straw
Items for Embedding