Brush(face) question

Can I make one of the faces on a brush dissaper without carving a hole
into it? So that whole face is gona completely so I can just jump into
the box?

Uh...you could try using the Hollow feature and deleting one of the walls I guess...

If I understand what you are asking, then you should just build that open box out of brushes, dont think there is another way to do what you are asking other than that or carve.

Ok thanks, but now how do I make a round wall? Curved?

round wall? Curved?

You build it brush by brush, or perhaps you can utilize the "arch"
tool. Read some of the tutorials for the original HL for
reference (look under "architecture").

The arch tool, or you can use the cylinder tool in conjunction with the clip tool and make the opposite of what you get with the arch tool.

Yeah, what they said. Cylinder + clip tool for convex rounded corner, arch tool for concave rounded corner.