The winding mandrel includes a pair of generally rounded-cube shaped or orthogonally flat-sided spherical main bodies connected together and having a plurality of cylindrical posts for forming vasoocclusive coils. The main bodies are connected together by a transition post, and the posts of the two main bodies are typically offset. A front end post and back end post are disposed on the front and rear ends of the mandrel. A short winding post member may be added between the connections of the two main bodies to provide additional winding posts.
