I found that the answer provided by @Marco was helpful but not the correct answer I was looking for.
Here is the general approach I used (Based on this).
- Create new document
- Import STL file
- Switch to Part workbench
- Select imported mesh
- Part -> Create Shape from Mesh (use default tolerance)
- Delete imported mesh
- Select shape
- Part -> Refine Shape
- Delete "unrefined" shape
- Select refined shape
- Part -> Convert to Solid
- Follow instructions in link provided.
Below is the list of instructions from #12
- Have shape loaded
- Switch to a plane that you would like to cut parallel to. e.g. XZ
- Switch to Draft workbench
- Draw rectangle around item to cut
- Upgrade using '^' up arrow (blue) in toobar
- Adjust the Placement Angle/Position via the "Data" in the property editor lower left side.
- Switch to the "Arch" workbench
- Double click the solid to cut in the 3d view
- Ctrl+click the plane you will cut with
- Select "cut-plane" and choose which side to capture
You will have to play around with the pattern in 12. The idea is to use the same Face created through 12 to cut the part at the same point twice. To create two halves. Take note of the position of the Face created in 12.
In my case, I was attempting to stretch the part along the Y axis, so I was able to cut the part with an XZ plane (created in 12) and offset with a distance in the Y plane.
After performing this "split" I created a cross-section of the at the point of the cut and extruded the cross section 3mm.
Afterward, I was able to use the Edit -> Alignment tool to attach all three parts back together.
Once attached, I selected all three and performed a "union" operation to make them all whole again, then executed the Part -> Refine shape.
End result was that I could make the chain links 3mm wider than the original.
I'm still working on tweaking out the other components that constitute this feature but still this is an interesting exercise.