Hi Tyler,
Since you want to cast this in a single pour, you will need to find a resin that let’s you mix and use that much at once. For the resins sold in our store, we list those details (minimum and maximum mixing amounts) in the PDF at this link: https://resinobsession.com/resin-frequently-asked-questions/resin-casting
I’m not aware of a mold for a casting like this. If you don’t have one, you will need to make your own. Do you have the templates to get you started with the mold?