Drag the transparency shader from SHADERS onto object A >> A gets transparent while other object stay opaque.
Drag the transparency shader to empty space >> All objects where you did not assign a special shader get transparent.
Hey I'm sorry, I was not clear.
I mean the surface under an object I'm working on.
To the surface that I can resize and fit into any 3D printer.
When the 3D object I'm working on is attached to a zero-height plane (Z-0) and I want to see it from below I need the surface to transparent.
With me the software is not transparent, is there a way to change it?
Ah I see, you need to disable ShowPrinterBed in the View menu by clicking on it (hotkey: Shift+Ctrl+P (Shift+Cmd+P on macOS)). To see the base plane as a grid you can toggle its rendering by ShowGrid in the same menu .
Great Thanks!