If you generate code from your fit, and then run that code, it will produce the same set of plots that you originally had but in a standard MATLAB figure.
- In Surface Fitting Tool, select File->Generate Code.
- Save the file that this produces in the editor (it defaults to "createFit").
- In the Command Window, run the file you saved, using the same variables that you used for the fit:
createFit(myXData, myYData, myZData)
This will create a figure and from here you can use any of the normal export tools for capturing an image, e.g. Edit->Copy Figure or File->Save As.