How to extrude from C-Plane to a Mesh?

Hello! I’m trying to create some small 3D printable topographies, but I’m having a really difficult time making an extrusion the same shape as the topograhy. Not sure how to articulate it, so check these pictures out.

I’m trying to fill the gap between that extrusion (the base) and the topography.
These are both polysurfaces, one from a mesh, the other from a silhouette of the mesh that I simplified.

I thought maybe to make my extrusion larger than the topo, and then use the topo to trim off the excess above the piece, but that hasn’t been working for me. Is this the right approach?

Could it simply be that these polysrfs are from a flawed mesh?

Thanks for your time :smiley:

Hello - try:

projectToCPlane > DeleteInput=No
Loft the original border to the projected one, with the seam point adjuster set to ‘Natural’


Note that if the goal is 3D printing, you do not need to convert your terrain mesh into a polysurface - and it may make your file size extremely large (polysurfaces take much more memory space than meshes). You will need to convert it back to a mesh for printing anyway, so you can also just keep it as a mesh to begin with.

Use the same general procedure as Pascal -

  1. _DupBorder to get the mesh outline
  2. Project the duped border to the CPlane (make a copy)
  3. Loft the two border curves as Pascal suggests
  4. Use the command “Mesh” to mesh the lofted polysurface, make sure “simple planes” is checked in custom mesh settings. That will create a mesh version of the “sides”
  5. Delete the polysurface.
  6. With the projected border outline selected, run _MeshPatch or _MeshPolyline (Mesh>From closed polyline). That will create the bottom “surface”
  7. Join all three meshes into one. If done correctly, it should be a closed mesh
  8. Export as .stl for printing.