Creating a custom 3D shape between 3d objects

[Anonymous]

Hello- I have an stl file with 2 major shapes that are essentially parallel with their individual surface topographies facing one another and a gap in between.  I would like to create a custom 3d object to fill this gap and have a negative on each surface of each of the 2 opposing topographies.  ANy ideas?

[Fadhil_Farook]

Any chance you can provide a video or some image reference of what this looks like? ie. Your present situation and what the Final one should be like.