I was reading this post from 2020. Because I use ReconstructCurve and Rebuild very often.

Michael > Rebuild is a built-in command, ReconstructCurve is a plugin.
When I started with MoI3D, the position of the scripts surprised me, then one day I understood (Eureka!): You can see, when you click on the "Scripts" icon, that the integrated commands are at the top (above the bar ) and below are all the plug-ins that have been installed.