How to merge/trim a solid and a surface



I was wondering if anyone knows how I can trim/merge solids which cut through surfaces. An image of my work is below. It is an architectural structure, and the part I need to trim are the levels (the parts sticking out). They need to mold to the shape. Does anyone know an easy way around this?

Also this needs to be 3d printed, does that mean my surfaces should be extrude slightly?



Good morning Nicole,

You will probably want to use the boolean tools to do this, but it might help if you uploaded your file so that we can see it.

For more information about boolean, you can start with the Help pages, and also look at the tips and frequently asked questions laid out here:

Hope this helps.



Thank You

I’ve been playing around with the boolean tools and not having much luck unfortunately but i’ll have a look at that reference and see what I can do.

Here is the file.

Thanks for the help


Since you are making intersection between solids and surfaces, you will need to be aware of the normals, or outside direction, so that you get expected results. Use the direction command to see which direction the arrows are pointing.

I also use a process that is a little more organized and predictable. First, you need to make sure that each solid & surface combo passes entirely through the other, so Rhino can find the intersection. Since booleans can be tricky, I do two splits – and it seems to work better than one boolean with complex shapes. See my free lynda video on the topic.

UPDATE: They have agreed to make my Boolean Tips Video free as well.


That does seem to work however it is splitting the side of the object I want to keep, know anyway I can get around this?

Thanks, the video helped!


If you are getting unexpected splits, then start with the OTHER piece of geometry first. For example, if you split piece A to piece B first, then split B to A first. When you get to your second choice, you now have options to split out only the part you want.