How to create an outwards bevel from an edge shared by 2 different cubes?

I'm stuck. Steps to reproduce:

  1. Start off with a plane, extrude up creating my "original base"

  2. Draw a Line (with Construction Lines add on), creating a new face on the "original base"

  3. Extrude that new face up, creating "cube A" -- [image_1]

  4. Draw 2 new Lines on the "original base" to create a new face

  5. Extrude that new face up, creating "cube B" -- [image_2]

  6. Select the edge that's shared between "cube A" and "cube B" -- [image_3]

  7. Bevel it, but it goes the wrong way... -- [image_4]

Desired output is an outwards bevel [image_5] between these 2 faces [image_6], not a weird inwards bevel.

Expecting a solution such as "merge faces" or "reverse bevel" to achieve desired output.

Thought about drawing the lines in step 4. above from "cube A" instead of the original plane, but at the end of the day I need to Bevel all edges so I'd be stuck in the same place.


image_1 image_1

image_2 image_2

image_3 image_3

image_4 image_4

image_5 image_5

image_6 image_6

  • $\begingroup$ Hello do you have a reference image of the result you want? or a drawing? $\endgroup$
    – moonboots
    Commented Feb 6, 2023 at 8:31
  • $\begingroup$ Well, you can only create a bevel between those faces if they are connected to each other. But since image 4 shows that the rear vertical edge of the front face is not connected with the larger face behind it, there cannot be a shared bevel between those faces. $\endgroup$ Commented Feb 6, 2023 at 9:34
  • $\begingroup$ Extrude Manifold might have helped along the way. $\endgroup$ Commented Feb 6, 2023 at 15:29

2 Answers 2


As Allen Simpson pointed out in the comments, Extrude Manifold is the answer. In short, Extrude ADDS geometry while Extrude Manifold EXTENDS geometry -- this video illustrates well the difference between them both https://www.youtube.com/watch?v=_xnCAIhSS6g

By using Extrude Manifold you're creating suitable geometry for the bevel tool to work with.


Here is a potential solution (sorry I don't have the addon so it's just with basic tools but I'm sure it can get you where you want).

  1. Instead of creating a face from the base and extruding it upward, start from the vertical plane:
    enter image description here

  2. Then extrude in the other direction:
    enter image description here

  3. Then apply a bevel:
    enter image description here

  4. Use the knife tool (K) to cut a straight line and clean the bevel:
    enter image description here

  5. Finally remove the unecesssary segments (Ctrl+X) and extrude the top faces:
    enter image description here enter image description here


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