what is this surface operation called (and can it be done in Fusion 360)

[rogercaplan]

Say I have at least 3 surfaces, e.g.

I want to create a closed surface that intersects each of these 3 "guide" surfaces, something like this:

[jeff_strater]

as far as I know, no, there is no easy way to make a surface such as this in Fusion without constructing a lot more scaffolding - guide curves, guide surfaces, etc. that connect to those seed surfaces.  Just curious about this formulation of the problem.  What is driving the question?

[rogercaplan]

The use case is designing a joystick grip - I start by figuring out exactly where all the buttons/trigger/etc. should be, then I "fill in" the rest of the object surface by doing what you described - guide curves, guide surfaces, etc.

[jeff_strater]

interesting use case, definitely.  I'll think about it a bit, but offhand, nothing easy comes to mind.  I thought maybe you might be able to do something with T-Splines and "Object Snap" to get, say, a quad ball to snap to those surfaces, but I tried it, and it didn't work so well...  Maybe someone more creative than me can come up with a good workflow here. 

[MichaelT_123]

Hi Mr RogerCaplan,
This could be looked at as a minimal surface or Dirichlet problem. It is not trivial, particularly for everyday calculator users and even for F360 machinery. Not surprisingly, it is easy for Nature itself, so with its always generous help, you might consider at least two (perhaps more) experiments generating such minimal surfaces. They are a soap and balloon experiment. However, if you are picky enough, immerse yourself in the relevant branches of mathematics.
As the issue is not new, there are many publications about the subject.

Regards
MichaelT
PS. The last second ... eureka! ...You can conduct a balloon experiment in Fusion-Simulation Workbench... probably.