Creating Solids, Using Difference, Adding dimensions to planes

So I am trying to take a mesh object, cut it in half with a plane and then difference the object from the plane so that I am left with a plane slice with a hole where the object once was. Unfortunately, being new to all this, I can figure out how to use the CreateSolid tool on my meshes as it wont let me select the object. Ive tried doing union, join, etc. When I finally do a difference, my plane looks like this:

I want a clean “plate” that I can then add width to. I intend to 3D print these outlines but first I need to be able to manipulate their shapes by adding width , as well as cutting them. Look forward to the answer. Thanks!

Mesh objects are not the same as NURBS surface objects. CreateSolid only works on Nurbs objects.

What you probably want to do is use something like Section to cut a slice through object and then clean up/rebuild the sections (they will likely be dense polylines). Or perhaps Contour to create multiple parallel “slices”…


Whenever I try to use either of those tools the contours are always running perpendicular to the axis which I want to use. I am essentially trying to split the object in half with a plane along its longest axis.

Contour or Section depend on the viewport you use.

Section projects a line onto the object in the active viewport CPlane direction.

Contour requires you to set a perpendicular axis direction with two points - when you do so, make sure you are not inadvertently snapping to something out of the plane which you want.


So thanks so much Mitch. Ive gotten to the point where I have sections, but when I make a surface and then try to difference those two I cant. Can you give me instructions on how I would a) fill in the section to make it a solid object and b) difference that section from a solid plane which I could add height? Thanks for helping a newb!

I’m not quite sure I understand what you need, but the section should be a closed curve if the mesh is closed - in that case the PlanarSrf command will make a surface from the closed section curve, or you could extrude it directly to create a thick plane with ExtrudeCrv Solid=Yes… Does that help any?

Otherwise, post the file here and I or someone else will try to create an example…


What I am trying to accomplish is to take any shape and create a wall of only a few millimeter thickness which would be the inverse of that shapes surface. If I were starting out with my shape as the river bed, I am trying to create the dam which would fit into that shape. It is necessary that the wall span the length of the object along its longer axis, as well as have adjustable width and height, and that I am able to cut that wall at any point to fit the object as I wish. I am trying to do this right now with this file, a scan of my foot. Ive gotten to the point where I can create a section from the plantar surface, but I cant figure out how to difference that from another solid “plate” and then cut the plate so that it would fit over the positive of the plantar surface of my foot.
foot.stl (3.93 MB)

Hi Yoni- is this about what you mean-

If so, select a contour curve and from the Solid menu, pick Extrude planar curve > Straight. Does that do it?


Thanks but Ive gotten that far and its not exactly what I need.I guess Im having trouble explaining this so its understood. If my object was a cookie cutter, all I want is the flat piece of dough with my object cut out of it. I want that sheet to be a thin rectangular solid which I can then cut and modify. Does that make sense?

Hi Yoni- OK, so you heed a bounding rectangle for each contour- BoundungBox will get you this for planar curves. Offset this rectangle by the amount of ‘border’ you want around the shape, and then with both the offset and the contour curve selected, Extrude planar curve > Straight. Dpes that do anything good?