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I am just trying to create a simple outlined heart for a 3d print job. So I modeled a curve for the heart and added a circle as bevel object. The result looks like I want it to have..

But switching to wireframe mode shows that the resulting object has intersected vertices / faces which will cause my 3d print to fail...

Is there a simple thing I am missing on my task to just get the outlined object without intersections?

Here is what it looks like and where my problem is:

intersected sections in beveled object

I tried to convert the result into a mesh and apply a skin modifier which took ages to calculate and did not work as desired. Also the solidify modifier did not work...

Thanks a lot for your comments!

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  • $\begingroup$ I would either generate only half of the object, duplicate and mirror to create a second half and then use bool to join them together (and keep my fingers crossed that it wont mess things up), or convert it into mesh, remove intersecting verts and fill holes manually. $\endgroup$ – internetofmine May 14 '18 at 8:51
  • $\begingroup$ Yeah... I already did that and it kind of worked on such a simple structure... but I got more complex objects I want to outline like the heart where a manual correction is not a really funny option... $\endgroup$ – Stefan Möller May 14 '18 at 9:21
  • $\begingroup$ I would try boolean operations then, generate a half, duplicate and mirror it. And then join them together using Boolean modifier. $\endgroup$ – internetofmine May 14 '18 at 9:23
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This may still involve too much hand-editing for you..

Create your profiled curve to produce a deliberate overlap with its reflection - (you're looking for a good clean cut down the Y axis) .. here the mirror modifier is only there to vizualise the result

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Having converted to mesh, in an orthographic view, Use the knife tool, constrained, to cut through the mesh (K),(C),(Z) Rip the selected edges(V, select the excess faces, (mouse over, L), and delete them.

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Add a mirror modifier with merge and clip, and in edit mode, bring the halves together until they just snap, and draw them apart again slightly.

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There may still be a few editing decisions on the seam, after applying the mirror modifier, removing tris, bringing some vertices together, but not many, if your mesh is not too dense...

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and the result is quite clean.

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If I understand you correctly, it seems to me that the only problem with your initial approach was you switched to a mesh at the wrong point and used modifiers that weren't ideal.

You could make your curve as you wish, and convert it to a mesh before adding the volume, so it is just a set of vertices forming lines. Then, by creating a minimum geometry that can be converted to the shape you want, you only have to adjust a few vertices, and it's quick if you know how to go about it.

  1. After you have created your shape, convert it to a mesh by pressing Alt + C. The mirror modifier will be applied in this process.
  2. In edit mode, select all the edges and extrude them perpendicular to the plane of the object. So, if you built the curve in front view (numpad 1), extrude along the Y axis.

enter image description here

  1. Join any detached sections present - select the edges on either side of gaps and press F, subdivide edges on the sides of the face closest to an adjacent group of faces by pressing W and selecting 'subdivide' from the pop-up menu, then slide the new edge to the right spot by pressing G G.
  2. Do this on one side and delete the mirrored side. Press A to select all edges and press Ctrl + N to recalculate normals. Add a mirror modifier again (now that it will build what you want). Don't merge or clip the things on the mirror axis. Instead, move one of the edges adjacent to the mirror axis to a distance equal to half the thickness of the final wireframe shape you are creating. Select any other edges along the axis and move them an equal distance away (pressing S, then X, then Numpad 0 will do this if they are all selected, the one that is already placed is selected last, and the Pivot Point menu in the bottom menu bar - 3rd from left - is set to Active Element).
  3. Add a Solidify modifier and adjust the thickness to what you want. Set the Offset to 0 so the shape being modified is in the center of the volume created by the modifier, that's probably the look you want. The corner edge of the pieces at an angle to the center axis will just barely touch together, that makes editing them easy. Apply the modifier.

enter image description here

  1. Delete most of what you just built. The parts that are folded in tight curves are the parts that get messed up, but it isn't very much to deal with if you are just adjusting one flat plane of quads. Go into top view by pressing Numpad 7 and if you aren't in orthographic view, press Numpad 5 to enter it. Press Z to get into wireframe view, then press B and draw a box around everything but the front plane of faces defining your shape. Delete them. Also delete one of the mirrored halves, it's easier to add it again later.
  2. Fix what remains. I use the knife tool (K) to cut across the problem faces, the circle select tool (C) to select the ones that were wonky, deleted them, added loop cuts (Ctrl + R) so the parts to be joined had equal segments to weld. Then I selected edges on either side of each gap, pressed Ctrl + E and Bridge Edge Loops from the pop-up menu. After pressing A to deselect everything, I pressed Ctrl + Alt + RMB while hovering over one of the edges between the now joined sides to select the whole row of extraneous edges there. I pressed X, and chose 'Collapse Edges' to join the pairs of vertices on either side into one row of vertices. Then I added the mirror modifier again, applied it, and joined the middle edges along the axis.

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enter image description here 8. Select all and extrude along the Y axis again until you have a square cross-section. Crease the edge loops that need sharp corners.

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Where you want an indent along a join, scale the line of edges on either side of that along the Y axis a little, and add a crease.

  1. Add a 'Subdivision Surface' modifier. 2 subdivisions seems to be enough for your purpose. You now have a mesh that is all quads, with no internal faces and smooth joins. It's a lot faster to do than to write down. (It's practice for me though, and payback.)

enter image description here

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Thanks for the work you put in your answer... That will work - of course - but as you said it is still a bit too much hand work...

enter image description here

The next item I want to outline is a tree... and for that the solution is really a bit too hard...

I got help from another forum: exporting to stl, importing in Microsoft 3D Builder, fixing in 3D Builder and Reimporting in Blender solved the issue... Not a great answer as it involves another tool but it works fast and easy...

Here is the result of the five objects I wanted to create: enter image description here

And a close up of the (fixed by 3D builder) tree wireframe: enter image description here

I just hoped to get a clean and nice solution from within blender...

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