Hi Burr,

> After seeing the way you used trim instead of the way I used
> bool diff, is it an either or, or is there an advantage to my
> model geometry to do it with trim?

Hi Burr, it all depends on what shape you want at the end - I was going for a kind of "thin wall" type shape without much bulk.

Your one is just as valid, but it has more material in it, more of the inside of the sphere remains in the way you did it.

If you have a solid and you want your result after cutting to be a solid, then boolean diff is the way to go though.

Another alternative way for the one I did would be to do the shell on the uncut sphere first, and then do a boolean with the cutting curve like you show, it just isn't quite as clear of an illustration because it is harder to see the thickness on the uncut sphere...

Booleans and trim are related functions - basically booleans are a shortcut for doing a trim and then automatically deleting certain parts (to the inside, outside, etc... depending on whether it is a difference/union/....) then joining the results together.

I was kind of focusing on the initial shape as more of a surface model instead of a solid model - for surface models (a surface that does not enclose a volume), then you tend to use Trim more often for that because the booleans are more oriented towards volume operations.

- Michael