An Offset surface, is a smooth surface (without edges, peaks, or singular points, where each point has a tangent plane. Examples: Spheres, ellipsoids, toroids, cylinders and planes), it is defined as follows:

sd[u, v] =s[u, v] + d n[u, v] and sd[u, v] =s[u, v] - d n[u, v]

s[u, v] it is a smooth surface, d = distance, n[u, v] it is the normal unitary vector to the surface s[u, v]. In this notebook we will obtain the offset surface of the toroid: {(5 + 2 Cos[u])Cos[v], (5 + 2 Cos[u])Sin[v], 2 Sin[u]} with d = 1.5.