How to Close and Solidify an Open Polysurface


How do I change an open polysurface to a solid? The model is also supposed to be about 2 inches thick, and I’m not sure how to do that.

The file is attached below. All help is appreciated!!

Thank you!

Topography_CNC.3dm (4.2 MB)

Hello- you have a bit of a mess there - bad objects - but apart from that there is some clean up and decisions to be made - for example, what do you expect to happen here?



Hi Pascal,

Thank you for your reply.

The topography and buildings in my file were taken from a larger model. I exploded the houses and joined the elements that fit the model boundaries.

That’s what the image here is showing. How do you suggest I improve it?

Thank you so much!

Hi -

That’s hard to tell without knowing what the larger model looks like.
As Pascal mentioned, start by extracting the bad objects and fixing those. Use DupBorder to find the edges that are open. If that doesn’t return a single border that you could extrude, then cut and join with a horizontal plane to create a solid, you’ll have to check all open borders and fix those.

Hi Wim,

Thank you for the reply.

I’m relatively new to Rhino, so may you please clarify what you mean?

The general site is now included in the file.

Thank you,

Topography_CNC.3dm (9.0 MB)

Hello- there is a lot to fix, it would be best if you learn a bit more about how Rhino works, how surfaces work, and how they are combined into solids - that will clarify a lot - for example you’d see that this is not going to work with your concept:


Please see -