How do I create an object that I can Select>Convert To.. >Open Part

[Anonymous]

I have created a simple object in TinkerCAD and I have opened it's stl file in meshmixer (file attached).

I want to add it to My Parts in Meshix, so I have to convert it to and "Open Part".

However, when I do that I can the following error (see attached image).

Any ideas?

I have created other objects but I keep getting this boundary loop error.

[Anonymous]

OpenParts support a single shell with an open boundary.

A default object with such an open boundary is the default bunny (its base plane is open) . Open boundaries are indicated by a blue line.

So if you do SelectAll and run ConvertToOpenPart its open boundary is used as a "contact loop" . 

Now if you have a "solid" part (as in your case) you'll need to do some partial selection. This selection needs to have a single "selection boundary loop" (means: one selected area with no faces missed in that area). E.g.: In case you want to get an open part from a bunny's ear, you need to select that ear all around and up to its tip.

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At your object:

- Your special object comes with a minimal mesh density (hit W to see the wireframe). You will need to generate a much higher mesh density via SELECT/Edit/Remesh first (MM will deform faces at the boundary to weld them with the target mesh) to get a satisfying open part from it.

- Fear you want to have the part to be welded to the target mesh on this surface:

You'll get a two boundaries part with two shells and bending issues trying this.

Use BooleanUnion instead (highly recommended)