How do I make a normal looking cave without TNT?

Can anyone tell me how? I'd use TNT, but it's disabled on Build 1.

A. Start with Worldedit
1. Give yourself a tool, like a stoneshovel
2. Select it(hold it in your hand)
3. Type //brush sphere air 5
4. Use this(right click where you want a hole) to make the cave, you can adjust the size with //size 4 replace 4 with whatever number you want

B. Smooth it out with voxelsniper
1. Give yourself an arrow
2. Type /b bb (This will give you a Blend(brush name) Ball(Shape name) brush, which you can use to smooth out the cave walls
3. Type /b 3 (replace 3 with a convenient size. If you set it too big, it will just erase your cave altogether, blending it into whatever terrain you dug it out of.
4. Select the arrow and right click to smooth out the cave walls to your liking.

Note: I used Worldedit and Voxelsniper because all you have to do is select a different item to quickly switch between brushes. You don't need to type commands.