Paolo has “managed to complete tools for conversion from internal units and metric (meters, centimeters and millimeters) for lengths, areas and volumes (LAV).”
Download these and put them in C:AutodeskDynamoCoredefinitions
https://docs.google.com/file/d/0B_gxi8GkU4FEelNHQkpVQ1hIOTQ/edit
Original post:
http://puntorevit.blogspot.com.au/2014/01/dynamo-metric-lav.html