Hey everyone I just signed up here and for the past couple of years I have been using Inventor 2011 to design sheet metal medical equipment however this has recently changed and I am now designing Architectural steelwork such as balustrades and staircases I have found the 3D sketch tool useful for drawing a rail on which to sweep the banister but I can only do this in a part file I cant seem to find an option to perform the same task in an assembly when creating a separate part it only seems to allow a 2D sketch  I apologise as I am sure this has come up many times (maybe even on here) bu I have been trawling the web for a couple weeks now to no avail so any suggestions would be greatly appreciated. Thanks in advance

I may be misunderstanding, but could you create the new part within the assembly, select the 2-d reference plane, immediately exit the sketch, and then create a 3-D sketch?