Hi NightCabbage, also there is an existing command called Shell which is related in several ways to the first 2 ones that you show.

If the piece you want to perform the inset on is a simple solid and not part of a large complex piece, then you can use Shell to help speed up those cases.

The way it works is like this:

If you have solid piece like this:



Select the faces that you want to have as openings in the shelled result, so in this case select these 2 faces:



Now run Construct > Offset > Shell, and enter a wall thickness value.

That will create this result:




Note that it is pretty close to what you are asking about - but it has more of a fully hollow shape rather than an indentation. But it has done a lot of the work already.

Now you can pick the inside bottom 2 faces like this:



Use Copy / Paste to duplicate them, then run Shell on those new surfaces to thicken them into a solid, you will need to set the Direction: Flip option in Shell to make them go in the proper direction.

That is the other use of shell, to thicken surfaces into solids - with that surface thickened into a solid, it is now a plug which fills in the hollowed out area, so you can now select the 2 solids and use Boolean Union to make the final result.




That sequence could be useful for doing some shapes like this pretty quickly right now.

- Michael