Split a closed volume

I laid out my components on a surface and then extruded a thin wall case around it.

I now want to split it into two halves clam shell style and split the halves. With this done I can add features so the two halves “nest”.

Any shortcuts on doing this? Brute force would seem to be to make a copy and start trimming…


Do you want to create a joggle on one side of the split case so that the case can be rejoined by slip friction? If so, you might Inset this piece and Join it to one side. The case looks to be open on one side. What type of features do you want to add? Trimming is more suitable for sketches. You have more powerful tools in 3D.



Thanks Tommy,

Yes on the joggle.

Actually it’s closed (I think) as I extruded from a shape one direction, then “pulled” the section symmetrically the other way. I then used the 2D pattern to create the flats on either side and chamfered everything. Handy was creating and orienting the components first then tracing the case around them.

As for other details, the case is pretty symetrical so I’ve been adding cutouts to the anticipated parting line of the case and adding ribs and screw posts - all surfaces that can be matched in the clam shell.

The last step will be to convert a part of the “long” side to a wraparound battery cover, probably also with a joggle.

Doing it all in 3D seemed to make sense right up to when I couldn’t figure out how to “split” the case into its two halves.


This seems pretty straightforward. I did it on a simple 10” square block to generalize.


Then I slid a copy of the block 5” (halfway); subtracted one half from the other. Rinse and repeat.


Then I shelled out both now 1/2 sized blocks.


Ignore the construction plane, I ended up not using it.

image image

Then I did a 0.05” inset from the inside of the shell, then another 0.125 and extruded 1” for the joggle/doubler. The 0.05 inset could be considered space for glue. Because it was hanging on the edge of the shell, I used the Transform tool to push it back 1/2 “.


And that’s it. One half slides into the other. With regard to the joggle, I could have alternatively done an outset of 0.05 “ and then slid it back and done a Union to its half. But I like to keep parts separate until I know my approach works.

Actually doing the post took much longer than doing the model! The forum editor does not adapt well to my 11” iPad Pro size.

And this is my good deed on this rainy day…