Hi

I imported a GLB model into my godot scene as a new node (drag and dropped it into my scene).
Then I added a subnode staticbody3d to this node. I also added a collisionshape3d subnode to the staticbody3d.

But I now get a message tell me this:

Can somebody tell me please how to do this?

Click on that node, then look to the details pane on the right (the Inspector tab). Hit shape then add new shape. Add a shape of your choice.
ALSO, when you have a mesh selected godot has some built in ways to create collision shapes for you. After clicking on a mesh in the scene tree look at the top middle of the viewport. There's a button titled Mesh, I personally like the option "Create multiple convex collision siblings"

Thanks a lot! I'm slowly understanding it now but still some questions:

I have chosen a boxshape3d. But this box is smaller then my model so I need to make the box bigger. I have a lot of models so it's a lot of work. Do you know if it's possible the box automatically resizes so my model is inside the box?

The button "Mesh" doesn't appear. Maybe this button is not there for imported models?

    blender-girl The button "Mesh" doesn't appear. Maybe this button is not there for imported models?

    Depending on how you imported the model, it might have a parent node but for the menu item to show up you need to select the MeshInstance node. Right-click and pick editable children. That should show the actual tree of the imported asset.

      I have the tree now but how you know what you need or what to do now?
      It's much longer then this

      Ah, on the "untitled" node there, on the right next to the visibility toggle there is a clapperboard icon for opening that sub-scene in a new tab. That will likely make it much easier to work with.

      Clicking on any of those meshInstances (in your tap titled instance_30...) should make visible the Mesh button in the top middle of the 3d viewport for what I described previous.