Abstract: An attachment surface for an implantable device has a random irregular pattern formed through a repetitive masking and chemical milling process. Additionally, an attachment surface for an implantable device has a random irregular pattern formed through a repetitive masking and electrochemical milling process. The electrochemical milling process is particularly well suited for use with substrate materials which have high chemical inertness which makes them resistant to chemical etching. Surface material is removed from the implant surface without stress on the adjoining material and the process provides fully dimensional fillet radii at the base of the surface irregularities. This irregular surface is adapted to receive the ingrowth of bone material and to provide a strong anchor for that bone material. The unitary nature of the substrate and surface features provides a strong anchoring surface with is resistant to cracking or breaking.