Grails: find domain class by name

I want to allow users to traverse the domain classes and print out dumps of stuff. My frist problem: assuming the following works just fine:

//this works
class EasyStuffController{
  def quickStuff = {
    def findAThing = MyDomainClass.findByStuff(params.stuff)
    [foundThing:findAThing]
  }
}

What is the proper way to write what I am trying to say below:

//this doesn't
class EasyStuffController{ servletContext ->
  def quickStuff = {
    def classNameString = "MyDomainClass" //or params.whichOne something like that
    def domainHandle = grailsApplication.domainClasses.findByFullName(classNameString)
    //no such property findByFullName
    def findAThing = domainHandle.findByStuff(params.stuff)
    [foundThing:findAThing]
  }
}



//this also doesn't
class EasyStuffController{ servletContext ->
  def quickStuff = {
    def classNameString = "MyDomainClass" //or params.whichOne something like that
    def domainHandle 
    grailsApplication.domainClasses.each{
      if(it.fullName==classNameString)domainHandle=it
    }
    def findAThing = domainHandle.findByStuff(params.stuff)
    //No signature of method: org.codehaus.groovy.grails.commons.DefaultGrailsDomainClass.list() is applicable
    [foundThing:findAThing]
  }
}

Those lines above don't work at all. I am trying to give users the ability to choose any domain class and get back the thing with "stuff." Assumption: all domain classes have a Stuff field of the same type.