I have a device with parts inside. What I would like to do is at some point show the inside part without "opening" the device, but I don't want to mess around with shaders and transparency. Is there a way to show this part kind of inside the device, but control the opacity so that it is visible from the outside? I know this can be done in compositing, but I am not familiar with compositing. Similar to the way the engine and chassis are represented in the picture.

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  • $\begingroup$ You don't want to mess around with shaders or use the Compositor but that's the 2 solutions that seem the most obvious ^^ You should do it through the Compositor, not so complicated $\endgroup$
    – moonboots
    Sep 16 at 18:44
  • $\begingroup$ Why don't you decrease the opacity of top? $\endgroup$ Sep 16 at 20:05

1 Answer 1


Transparency is easy if you use the video editor: Render two images, one of the part of the car you want to be transparent and one of the parts you want to reveal.

Then take those images and put them on the video\picture lines. (Go to your files to drag and drop the picture) Make sure the part of the car that turns transparent is on top!

Then find the opacity setting of the top picture and key frame it where you want the reveal to start and end, making sure to key frame the reduced amount of opacity where it ends.

If you plan to render a sequence of fancy turns with the camera, render two videos and follow the same process.

  • $\begingroup$ I know that's doable this way, but I really don't want to render. I also know that it is possible to have an object ID in the render pass and use compositing. When I am doing training on the device, I usually share my screen with Blender and go over the parts of the device. I wish there was a way to reference a model, it seems like it would have been of use. Sometimes I also recreate models from some CAD drawings with really bad topology (exported from SolidWorks, Autocad, etc.) and it would have been really nice to have a 3D model as a reference as well with opacity control. $\endgroup$
    – AK_
    Sep 16 at 20:17

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