Alignment and fitting of two object to each other

Dear all,

I am coming back to Blender after a long absence to prepare some sketches for scientific purposes.
I encountered a problem which is pretty basic but I have not found a solution to it yet, thus I hope to get a good hint here.

Basically I have a transparent 3D cone and a thin disc/slice of the cone is supposed to be opaque and move along the cone. I have already trouble after the initial cone modelling to fit a thinner cone shaped disc in it which fits snug to the initial one. I assume clever use of snapping options of the two meshes will help here but I have not managed an acceptable solution yet. This would result in a static solution. In order to animate, I think the inital cone can be used as some jkind of path because the moving part has to shrink accordingly.
Unfortunately I cannot provide an attachement as new user, so I hope the description is sufficient.

Best regards,
Mike

Here’s a suggestion (I have no ideas for snapping or anything else) - if the mesh geometry does not matter, you can use a boolean modifier to cut away the slice that goes outside the cone.

Cone%20Boolean
The slice is a square plane with a boolean modifier attached to it.

You could also duplicate the circular mesh part of the cone to be sure tu have the same number of segments on it. Use P in edit mode to separate the duplication. And use shrink wrap modifier on it over the cone. Then animate along Z axis.
It ll do the same thing. I don’t know which one of those techniques will be less resources consuming.
Should be interesting to compare on resources manager.
Cheers

I just tried using a shape key. Cut through the mesh near the base, select the edge loop, make a face. This is your ‘base’ shape. Add a shape key, using ‘gg’ edge slide the face up the cone, it will shrink as it moves up. This is your second key. You can then animate the shape key value to move it up and down.
Blend file attached.ShapeKeyTestCone.blend (1.6 MB)

Awesome! Thank you for your support. I will dig through the solutions the next days to properly understand how it is done.