We have developed a set of tools to build 3D images of vascular structures from contiguous slices. Slices were obtained from plastic-filled vascular casts. Major vascular branches on each slice were revealed and observed under the optical microscope. A series of video images of the branches on contiguous slices were then digitized. Each image was processed to isolate the vessels of interest. A user interface was built to select diameters, depths, and branching angles. A 3D image can then be viewed from any angle.