8mm nut output from Giles Bathgate OpenScad Metric Fastners http://en.wikibooks.org/wiki/OpenSCAD_User_Manual/Libraries#Metric_Fastners_by_Giles_Bathgate . It has been trimmed back to work as a Jam Nut basically backing up your 8mm (or 5/16 imperial) to a work similar to a nylon insert lock nut. or you can just use it instead of a real nut in non-critical applications.output .stl for any nut from an OpenScad library, center (rotate if need be) and place on your build plate in Replicator G. you can go back into skeinforge and duplicate/array to fill up your build platform if you need a large number of nuts. use the difference command in OpenScad to adjust your nut size to create the thinner Jam nuts. (see http://www.boltdepot.com/fastener-information/Nuts-Washers/Metric-Nut-Size.aspx for sizes). If you really want to do it right adjust your inner diameter and run a thread cutting tool inside of your nut some to get the threads started (but not completely).