//***Save this file to your ZBrush /ZStartup/Macros/Misc folder and press Macro>Reload All Macros
//ZBrush macro by marcus_civis July 2013

[IButton,???,"Export OBJ sequence from Undo History",
  [If,[IExists,Edit:Tool:UndoCounter],
    [VarSet,fileName,[FileNameAsk,"OBJ(*.obj)|*.obj||","mesh.obj","Save file..."]]
    [VarSet,fileName,[StrMerge,[FileNameExtract,fileName,3],"0000.obj"]]
    [VarSet,numUndos,[IGetMax,Edit:Tool:UndoCounter]]
    [Loop,#numUndos,
      [ISet,Edit:Tool:UndoCounter,[Val,n+1]]
      [FileNameSetNext,fileName]
      [IPress,Tool:Export]      
      [VarSet,fileName,[FileNameAdvance,#fileName,4]]
    ,n]
  ]
,,1]//end of macro