I posted about Randomizer a while back.  I have since seen it used to randomize the colour of panels.  One way to do this is to use a integer or numeric Shared Parameter and View Filters (ie. randomize from 1 to 5, have your View Filter apply Red to 1, Yellow to 2 etc).  However, could this principle be applied to change the actual Material too?

Philip Chan provides one answer:
In the component family environment, Revit won’t allow you to formulate the material parameter. All you can do is to set the material as a parameter; in the formula field, you won’t be able to input formula like you can for other type of parameter (e.g. Length). I recall a trick from Alfredo Medina that you can parametrize a material with conditional statement using nested family. So, I ended up rigging up a curtain panel family with a setup that looks like this:

you can download it from the link below:Randomized Panel rfa

Read the whole post:
link here

From Philip Chan’s blog:
The concept is simple, I make a Generic family (it can be any category actually) as a solid (in this case, just a simple extrusion), let the family intercept the curtain wall, then use “Cut Geometry” to cut out the curtain panel.

Once I made all the cut in the curtain wall, I have a yes/no parameter to control the visibility of the solid so that I can “turn off” the solid. As a result, it would appear that the curtain wall is cut out by a void. The good news is you can use the same family to make multiple cuts and it will work on the mullions as well.

Read more:

Another nice workaround by Philip Chan – if you want to change one of Revit’s built-in Type Parameters (derived from a Family Template, such as Door Fire Rating) to an Instance Parameter, you just have to take the Family on a little round trip to a more flexible Family Category.

For example:

  1. New Door based on Door Family Template
  2. Switch to Generic Model Type
  3. Change built-in Type Parameter for Fire Rating to Instance
  4. Switch back to Door Category

You can read Philip’s whole post at:
Phil-osophy in BIM: Hacking System Parameters in Door Family