I've just uploaded my first couple of pieces to shapeways and in each one of them they have an extra face or are missing a face of the object. I've been using sketchup and everything looks okay in it, is there anyway to double check my files before uploading them?
I stole this suggestion from Stop4Stuff (Paul) but yes, check it with NetFabb Studio Basic Usually missing faces are the result of inverted faces (they are facing in when they should be facing out) or overlapping faces.