How do you build cave entries / caves

Hi all thanks in advanced just wondering kinda new at this how do you build caves and there entries

Use a modelling program such as 3ds Max, Maya or blender to create a model which you can import into unity.

Blender is free so it's what I'd recommend.

see this Caves and underground bunkers - Questions & Answers - Unity Discussions
and look at “winamp monkey” in youtube to see tunnels generated with metaballs, there are metaballs script in unity community, else i was going to make some tunnels with xenodream or some generative code… gen code is EASY to deform a long cylinder and bend it around etc, add noise, apply diameter functions… Then… flip the normals inside the cylinder so have textures on the inside. but it is more difficult to make caves with multiple branches and forks etc.