Hi zsouthboy - for sweeping a thing like that directly you would normally need to set up the curves so that there were 2 curves and then use those 2 as rails for the sweep. That would probably mean joining some curves and using Trim at the mid-way point to cut the one on the back into 2 pieces.

But yeah if I understand correctly you would normally want to have a solid there and then trim off a piece of the solid with a side profile curve.

This previous post may help some:
http://moi3d.com/forum/index.php?webtag=MOI&msg=1359.2

I'll see if I can cook up some examples for your specific case here though - normally for cutting a solid I guess you would build this as a kind of bigger block to start with instead of building it up with those thin walls on that upper piece to start with.

- Michael

hi zsouthboy - here is another method you can use to build a top piece on your popcorn maker.

If you select these 2 curves:



You can then use Construct / Loft to build a surface between them:



Repeat this along the way, doing just a pair of curves at a time, and when you get to the top, select these edges:



And since that area if flat, use Construct / Planar to build a planar surface there to that outline to fill it in:



I'll also try to show you an example of a different way to construct things with thickness rather than this way.

- Michael

Thanks Michael, didn't occur to me to try a loft. I'll give that a try.

Still seems like there is a better solution for this, so I'm open to other suggestions.

Here's kind of a different way that you might approach building a shape that you want to have end up with a thickness to it.

This way uses the Shell tool to create the thickness at the end instead of trying to model the thickness directly along the way.

With this method you focus more on the full exterior shape of the model first.

Just a quick example - here I start with a curve:



Extrude it to get a solid:



Draw a profile curve in the side view which will be used to cut the solid:



Select the solid, then run Construct / Boolean / Difference, and pick the profile curve as the cutting object. This will cut the solid into 2 pieces, and you can delete the top piece, leaving you with this result:





Now to create thickness, select the front and bottom faces (note here the whole object is not selected, I have clicked a second time on it to drill-in and select just 2 faces of the solid instead of the whole thing):



Then you can run the Construct / Offset / Shell command to create a wall thickness:




This way tends to be easier to work with the kind of outside form of the shape first, that way you can carve off pieces with booleans easier and leave the full width of the kind of "imprint" of the carving piece.

If you have modeled a solid that already has a thickness to it, then when you carve off a piece of it from a side profile, it will only leave the "imprint" along the part inside the walls since that is the interior of the solid...

Does that make any sense?


Otherwise the way that you did it initially of building it more directly to the thickness by surfaces at a time would need to continue that route and build more individual surfaces like by the lofting and Planar methods that I showed previously. That's kind of a more "low level" approach building it a piece at a time instead of working on the outer solid initially.

- Michael

Tricky shell function as usual :)