This routine from Alan Thompson shows you the power available in AutoLISP, using minimal code. It allows you to graphically and dynamically change the arrowhead size on a multileader in AutoCAD. While this may make some CAD managers cringe at the thought of their standards being easily abused, I certainly see value in this routine. Even if you don't need to alter mleaders, consider the other possibilities you could achieve by slightly modifying the code. Start by loading the LISP file, then type in the command name ArrowheadScale. Select an mleader, then watch as your cursor defines the arrowhead size. Remember that the maximum allowed arrowhead size is a function of the length of the first leg of the leader. If you drag the size too large and the arrowhead disappears, simply repeat the process and choose a slightly smaller size.