Two transformed cubes:
![](https://developernote.com/wp-content/uploads/2023/10/image-3.png)
Applied bevel tool:
![](https://developernote.com/wp-content/uploads/2023/10/image-4.png)
Applied smooth tool:
![](https://developernote.com/wp-content/uploads/2023/10/image-6.png)
Applied bevel + smooth again:
![](https://developernote.com/wp-content/uploads/2023/10/image-7.png)
There was the following icon in the right panel:
![](https://developernote.com/wp-content/uploads/2023/10/image-8.png)
it means that the object is in Edit Mode:
![](https://developernote.com/wp-content/uploads/2023/10/image-9.png)
Cutting with another cube:
![](https://developernote.com/wp-content/uploads/2023/10/image-10.png)
![](https://developernote.com/wp-content/uploads/2023/10/image-11.png)
With hidden cutting cube:
![](https://developernote.com/wp-content/uploads/2023/10/image-12.png)
Subdivision does not make it smother:
![](https://developernote.com/wp-content/uploads/2023/10/image-13-1024x502.png)
But subdivide + smooth probably does:
![](https://developernote.com/wp-content/uploads/2023/10/image-14.png)
![](https://developernote.com/wp-content/uploads/2023/10/image-15.png)
There is an alternate way with a bevel modifier:
![](https://developernote.com/wp-content/uploads/2023/10/image-17.png)
![](https://developernote.com/wp-content/uploads/2023/10/image-16.png)
How to CUT an OBJECT with another OBJECT in Blender – Boolean modifier
https://www.youtube.com/watch?v=LCzCi2_hX3w
3 Ways to CUT HOLES in Objects in Blender
https://www.youtube.com/watch?v=kUwra0cM4To
3 ways to Slice Objects | Blender Secrets
https://www.youtube.com/watch?v=yFy0kiAIUXQ
How to round edges (Blender tutorial)
https://www.youtube.com/watch?v=bZQeZUly9h0
A better way with Bevel modifier + Shade smooth:
Blender 2.91 Tutorial: Create A Cube With Round Edges And Corners. The Easy Way.
https://www.youtube.com/watch?v=9NYDnjotQbc
Separate vertices:
How to Round Edges or Corners | Blender Tutorial
https://www.youtube.com/watch?v=wcCB4Nkoxfo
Modifier:
Blender Tutorial – How to Bevel in Blender
https://www.youtube.com/watch?v=LVvhdZszwqU
Tutorial: Blender MODELLING For Absolute Beginners – Simple Human
https://www.youtube.com/watch?v=9xAumJRKV6A&t=254s
Extrude, Scale:
ABSOLUTE Beginner Basics.. Blender For Noobs
https://www.youtube.com/watch?v=Z8sg0nHNTTo
O + G:
Proportional Editing in BLENDER (Micro Tip)
https://www.youtube.com/watch?v=FWZKwU5-u18