Rotating Brushes

In this tutorial I'll show you how to make grouped
brushes rotate by way of making a classic ceiling
fan.  You can use this function for a whole variety
of cool motion effects.

First  make  one  of the  blades by creating a rectangle
brush with two tapered brushes at each end like the
pictures  below.   With  the  three  parts  of  the  blade
selected hit the space bar to clone the blade and use
the z-axis rotate button to move them into place.  

   

Now  in the center of your new  creation place a brush
that  is slightly  higher and lower then your blades but
make sure it touches the end of all four blades like the
image below.   Use  the  'common'  then  'origin'  texture
to cover this new  brush.  Now  simply  select  all of the
brushes  and  right-click  on  the  2D  veiw  and  select 
'func'  and then  'func_rotating'.  When  you  deselect
you'll notice that the brushes in the 2D veiw are blue.
They  have  been  transformed  into  a  grouped entity
that now rotates.  The origin brush is the axis that any
selected  brush  will  rotate  around  as  long  as  it  is 
touching that brush.  If you want to change the speed
of the rotation just select the grouped entity and hit
the  'n'  key  to  bring  up  the  entity  menu  and  enter
'speed' in the value field and a numerical value such
as 25 in the key field.  Remember that these brushes
are  solid  and  will  kill  players  pinned  between solid 
objects. Now it's time to finish our new creation!