Sketchup needs a Knife tool

I have been working on this for over 3 hours, and for the most part, I got what I wanted, except one thing, the resilient channels are IN the doorway, and I want to “Slice” the part of the Resilient Channel that is in the doorway, I tried to do it three ways, Extensions, Planes and manually drawing lines around the intersection, and neither achieved the result i was aiming for.

Here is the file, if you think you can do what I was trying to achieve: https://www.mediafire.com/file/6md3wkfp0lhcxgn/Office.skp/file

The overall intent of this file is to get exact specs for my Dream Office, of my Dream house(Which I need to 3D model all the rooms and whatnot for) so ultimately I can convert my model into blueprints that I will take to a builder to get a quote on how much it would cost exactly to get this house built(yes that is the long term goal).

I am thankful if you can successfully do what I failed to do, but if you can’t then no worries, I’ll do what I want to achieve the very hard way(Copy the resilient channels resize for one side, then paste resilient channel to other side and resize that)

P.S. I remember when I was in school, SketchUp had a “Walk” Feature which made it so you could explore your 3D model as if you were actually IN SketchUp, so where did that feature go?

So I got rid of the top one with no problem using a couple of rectangles as cutting planes and Intersect Faces after I drilled down through the component and group containers to get to the raw geometry.

If you had made the thing a solid group or component without all the nesting, cutting would have been a simple matter with the Solid Tools.

As for the Walk feature, it’s still there in the Camera menu and toolbar.
Screenshot - 4_5_2020 , 8_30_39 PM

What version of SketchUp are you using? Please complete your profile with that information.

I tend to use SketchUp Make 2017.

I have to admit, I still need to learn some Of SketchUp’s more convenient features.