Creating a negative for vacuum forming from a STL

[Anonymous]

Hey all, I am really new to Fusion and a student. I am on my 3rd day using Fusion.

I am trying to generate a negative out of wood. After I CNC it, I will vacuum form Kydex over it. The issue I am having is that I need to have a the mold reflect the bottom of the part. Here is what I have now:

I know I did not do this correctly. I duplicated the mesh, removed a bunch of it, then scaled it on the X and Y. If anyone can point me to a tutorial to do this, I don't know exactly what to look for. I guess the best way to describe this is creating a lip so the Kydex forms to the bottom angles.

In case anyone wants it, here is the original STL file: Thingiverse.

I plan to use this with 3mm Kydex. After I form it, I will place it back on the CNC to cut the excess off. 

Thanks.

[etfrench]

One tedious way to do this is to delete the outer faces.

• Start by changing to Direct Model mode: Right click on to node in the Browser, then select 'Do not capture design history'.
• Convert the stl to brep.
• Delete the outer faces.
• Change to Patch workspace
• Thicken the remaining faces

You may want to extend the faces around the edge before thickening.

p.s. If you need the mold to be slightly smaller than the finished product, then you can do this in CAM.

p.s.p.s. It would be a lot easier to delete the faces using MeshMixer.

[Anonymous]

How would you do this if your stl file has a ridiculous number of facets? for the negative that I am working on, converting the stl file to a brep just locks up Fusion.

[etfrench]

Meshmixer actually works much better than Fusion 360 for deleting faces on an STL file.

[TheCADWhisperer]

I would use the stl only for reference in remodeling proper geometry for the part and mold from scratch.