Need help to transfer details of a concrete mold onto the finished product



I am designing a concrete fireplace mold that will have removable void displacement boxes so that I am left with an imprint of the details. I am trying to mock up what the finished product would look like, but have no idea how to transfer some of the details of the mold onto what would be the finished object due to the chamfers, mitres, angles involved.

Thanks so much.

Not sure how to communicate what I want clearly with photos as a new user is only allowed one photo, but hopefully its clear.



It is the details of the top of the fireplace that I am struggling with.


You could use a copy of the core that you’ve already made.


Wow! you sure made that look easy!

I am struggling to duplicate that result. How are the pieces of the model grouped (or not grouped) to get that result by deleting that one line?

I should also likely ask you how you were able to mock up my chamfered and mitred details quickly enough that you were willing to do them to answer my question, as it took me a looooong time to accomplish that! :slight_smile:

THanks so much for your reply and solution!


The trick here is that @DaveR is making use of the ‘stickyness’ of SketchUp, nothing grouped, yet. Once placed, the edges merge. To make the mitered details, the Follow Me tool is appropiate, select the path, first and then activate the Follow Me tool, then, select the face:

Here, I use Shift to extend the selection and ‘Offset’ only three edges.
It is wise to draw a face in the right plane (Press Arrow keys for direction) Then draw the outline ‘on Face’

Still, everything is plain ‘raw’ geometry, nothing grouped.

For the actual mold, the same thing aplies, draw a rectangle to draw the miter and chamfers:

Again, nothing is grouped: Rotate the selected geometry of the mold, activate Move tool and pick the center to move it to the right spot on the chimney.

Erase the edges (those lying on the ground were ‘internal’, so they will wind up in the mold as well…)
Right-click on a face that has the right direction (White colored, my back face color is red, @DaveR 's is green) and select ‘Orient Faces’

(You can now group the mold…)

chimney.skp (430.5 KB)


As Jack said, In my case the geometry wasn’t grouped. If your core is grouped you would explode the copy so that the geometry of the core and the fireplace mass is all in the same context.

I just eyeballed it from your screen shot. It wasn’t nearly as much work as what Jack shows. Just a few edges to draw the half-profile and three sides of a square for a Follow Me path.


I just showed the whole process, showing only the Follow Me step, does seem faster, though😃

But the path needs to be exact, otherwise you will wind up with a bunch of extra work, that is why I always try to learn my students to pick the path out of the existing geometry, especially in the beginning.