A year ago, I asked how to make a mold using an imported STL file. With the community help, I was able to get the mold to work.

However, this was importing the STL as a solid, and with this many facets/triangles, Solidworks can have awful performance. This will bog me down as I try to make multi-part molds with several components.

So, I'm trying to redo the exercise, this time importing the STL model as a graphics surface and generating a Tooling Split. Here's what I did:

1. Import the model as a graphic surface/body
2. Used the "Decimate Mesh Body" tool to reduce the amount of polygons by 40% (making the model ~29,000 facets)
3. Used the "Convert to Mesh Body" tool to turn the graphics into a mesh body
4. Moved the center of mass of the part to the origin (just to make the surface work simpler)
5. In the "Split" tool, used the front plane to split the part. This created "Split1[1]" and "Split1[2]" under the Solid Bodies folder
6. Created a sketch on the front plane, and used a corner rectangle to make an arbitrary sized rectangle
7. Used the "Planar Surface" tool to turn that sketch into a Surface-Plane
8. Used "Trim Surface" tool to create the parting surface which I will use for the parting surface for the mold "Tooling Split" tool.

I can't seem to make a Tooling Split from here. It appears this is because I'm not creating surface bodies through this process. What can I do to fix this and get a Tooling Split to work? I've tried to use the "Convert Mesh to Standard" tool on "Imported2", but this complains "Selected entity is not valid for the current feature." I'm also not sure if that's the right approach.

Part file attached below (SW2025 format):

Thank you for your help!

@Tadaharu Sakamoto, would you be willing to help with this problem, too?

SW2024 version of the same file: