I recently started playing around with rhino and GH. I want to make some Christmas presents for my parents- candle holders. I have attached the model.

I want to 3d print them but beforehand I want to know what the volume of the shape is. After modelling it in Rhino I opened GH, typed Geometry and selected the shape. Afterwards I used the function Volume but it turned red saying that it is an open brep. Is there a way to find out where the problem is and can the problem be with GH (well by GH I mean me)? Is there another function to which I can assign the geometry and another way to find the volume?

You can see naked edge with the ShowEdges command, set it to show naked edges. In this case you have a lot of naked edges so it is indeed open at a very microscopic level. How did you model it?

Well put it simply I did a cylinder, carved out the space for the candle, afterwards i did the triangles, rotated them accordingly and then polar arrayed them. In the end i did Boolean union. I think in GH will be very easy seeing what people are doing, but I can’t really do it.