This is a big and deep cave if you want to you can modify this and make it bigger wherever you want to, I suggest tinker cad and import it to tinker cad and make it how you want it. 

Version 2 of this is now out this one is deeper and bigger on the inside and will print better with overhangs. The link is below. ⬇

https://www.printables.com/model/1054771-bigger-and-deeper-cave-v2