How to create a geometric edge on an object?

Hi, im new to rhino, i am using the mac version if that makes any difference, so far ive managed to create what i want to a fairly accurate degree, and 3d printed it with great success. now progressing my idea forward i will do my best to explain, i have a wheel or ring shape if you like, and on the inner rings edge, i want to create a geometric assortment of triangles that eat away at the edge, so they look pushed in almost, i want them to look seeminly random in size and position, but i want them to be all the way around the inner rim, and all connected. my best example of this effect would be,

this look, but imagine it around an edge of a circular hole. i know how to extrude a shape up, but if i wanted to draw a shape and push into the edge, how can i do this?

i hope that makes sense, if not please let me know.

thank you

Edit. I do have access to the windows version is well, in my university.

Arran Gregory’s sculptures are heavily influenced by the ‘low poly’ art movement that’s being doing the rounds for the last couple of years. And by definition most of this artwork is created in poly modeling packages such as Modo, C4D, Max & Maya (there’s a wealth of others too including the free option Blender or low cost options such as Silo).

The Grasshopper plugin could be of help here if you were on Windows but it’s a long way off being implemented into the OS X version. of Rhino. There are poly mesh options available in Rhino but I personally never use them as they’re not Rhino’s strength (much as the Nurbs stuff in Maya is pants!).


Instead of trying to push around the existing edges - something which will be difficult if not impossible - you will be better off creating a positive shape as a “cutter” and subtract it from your ring… that will give you the desired effect.

Now, as how you go about modeling the cutter:

You could create something manually with a pseudo-random effect, for example create a pyramid to subtract and array it around the ring edge, then start point-editing the pyramids (with SolidPtOn) a bit randomly, then subtract; or, if you’re adept at programming you could create a Python script that would use a randomizing function to do the same kind of thing. Grasshopper would be a nice way to go, but as it doesn’t run on Mac…