How can I slice out the middle of a solid object (shortening it without scaling it)?

How can I cut a section out of the middle of a solid object, shortening it? For example if my object was this couch:

How could I make each of the cushions 20cm narrower, without scaling the entire object down?

I’ve read the solutions at forum post “Make the 3d models longer or shorter”.

But those solutions don’t seem so easy to apply. Like the couch, my real object has sort of messy geometry at each end and thus it’s hard to imagine correctly selecting all the relevant geometry. I wish to shorten my object by a given distance (say .2 inches), removing a section from the middle.

You can use the T2H_STRETCH_BY_AREA plugin By TAK2HATA to easily stretch your model or parts of your model. This stretch goes through groups and components. Only watch out for dynamic components. This tool will convert dynamics into normal components!

This is a awesome plugin!!!

t2h_stretch_by_area.rbz (12.7 KB)

That looks like a simple object. If you just pick one side of the cushions and move it 20 cm it will work great ! Same applies for the sofa.

As of plugins I know that Fredo’s Scale has the Stretching with orientation of scaling box tool, which will stretch keeping the sides untouched.

@ely862me my actual object is hard to select. With the couch, selecting
one side of the cushion won’t shrink the entire couch.

Have you tried the dynamic component “Couch”, from the “Components Sampler” collection ?
(This collection comes installed with SketchUp.)

You place one of them, then choose the ScaleTool and it is programmed so you can only stretch it in it’s longitudinal axis. The cushion sub-components will be stretched and copy cuchions inserted as needed to meet the “Width of Cushion” option in the DC Component Options dialog.

This should give ideas, even if you do not wish to tackle dynamic components yet. Ie, the cushions should nested groups or components themselves.

Just FYI,… in SketchUp the MoveTool is the general purpose manipulator, which does stretching as well as moving.

Draw a rectangle on the ground plane, and pull it up into a cushion with the PushPullTool.

Hit spacebar for SelectionTool, and select one of the end faces.

Hit M for MoveTool and grab one of the selected face’s vertices, and drag it along the edge perpendicular to the selected face.

That is stretching in SketchUp, using the MoveTool.

You didn’t upload your model, so it is hard to illustrate specifically, but the technique @ely862me recommended is easy and uses built-in tools. The main trick is to view hidden geometry before selecting so that you get all of the potentially softened, smoothed, or hidden edges. BTW if you can’t select the end of a cushion without getting other geometry, you probably haven’t grouped or made components correctly.