By using the simple in-game 3D modeller, or by using an external 3D modeller and importing meshes. Plus time writing or adapting scripts in SL's scripting language, if there's any interactivity needed.
It is a similar amount of effort to what goes into making the equivalent object in a 3D game, and if you have the skills and the time, sure, clone other people's stuff, or make your own riffs on them!
Wouldn't it be possible to rip the mesh of the existing object directly out of the game client's memory? And then import it again as a new (copyable) object.
It is a similar amount of effort to what goes into making the equivalent object in a 3D game, and if you have the skills and the time, sure, clone other people's stuff, or make your own riffs on them!