About this 3D model

who invent thread less one screwball？ thanks this one first, I design a new one for 3d print and pcb drill, nice one! accurate and no shock. skype:zhongxw_oftenfull.com mail:homer@ideaone.cc www.ideaone.cc anyone wanna see samples? I could send to you. skype:zhongxw_oftenfull.com http://3d1st.taobao.com/shop/view_shop.htm?user_number_id=1143920&spm=a1z10.10.w4039-1552525805.2.mUVSk4 http://item.taobao.com/item.htm?spm=a1z10.1.w137644-1552541310.49.29W0vr&id=36764039130