Mapping/Pipes

How to create pipes

Step 1 - create a square brush

Step 2 - select Brush->Prism - enter e.g. 24 and hit ↵

Step 3 - Mark this brush, hit Space to copy it - and select Modify->Arbitrary Scale - change x and y to 0.8

Step 4 - now hit the CSG-Substract toolbar icon or hit Shift U

Step 5 - now delete the inner brush by hitting Backspace

Step 6 - final result