Hi Jay,

re:
> For example, I now realize that MOI doesn't really know something is truly "solid".

Actually it does - an object that has a watertight skin will be recognized as a solid, it will show the object type as "solid" here:


it will also work with the boolean commands and in v4 you can calculate the volume of it.


> I proved this theory to myself by using "Draw Solid" to make a cylinder, and then cutting that cylinder.

Your result will depend on what tools you used to do the cut. If you use the Edit > Trim command, that one is focused on surface level operations and not on volumes. The boolean commands are the ones that work with volumes.


> So to answer my question, "Creating this as a solid" means creating faces that all intersect, or
> meet each other with no gaps. Faces can be created with "Network" or "Planar" commands.

If you have constructed several surfaces that touch each other with no gaps, you can use the Edit > Join command to glue them together into a connected watertight skin and that will result in a solid.


> In another post, you had a link to a zip file that would create a "plug-in" that would help resolve this kind
> of problem (I guess) but I can't find any documentation about how to install a Plug-In into MOI.

Check out the Frequently Asked Questions page: http://moi3d.com/FAQ#Q:_How_do_I_install_a_plug-in_script.3F


> So can you help me perfect my work method and know how to get the base connected to the top?

You would normally use Edit > Join to glue the 2 surfaces together, but you have too large of a gap between them for it to be able to join.





The gap is a result from 2 of the curves not touching the bottom one:





In the attached 3DM file I've tuned those curves up to make them end directly on the bottom one, then did Construct > Network to build a network surface then selected the surface and used Construct > Planar to fill in the planar bottom opening to make it a solid.

Hope this helps!

- Michael