Thanks to

Pior "pior" Oberson
for the original concept

IllusionCatalyst ExtendSurface extends an Editable Poly surface from its border. If no elements are selected, all borders are extended.

  1. Select a set of Edges or border elements
  2. Run IC.ExtendSurface
  3. Drag Up to increase surface extension, down to decrease
  4. Drag Up/down pressing CTRL to adjust extension slant
  5. Right click to exit the command or left click to start another extension

Note: Undo can be performed only from Main toolbar button or by pressing CTRL+Z after stopping the tool.
Autodesk 3ds Max 9+
Additional requirement for 3ds Max release 9 only
AVGuard MAXScript Extension Package 9.0.0 by Larry Minton
Download — version 0.2 — 2009.12.09 — 4.53 KBytes
Discussion thread on Polycount forum