Right, most of these don't work unless you make some adjustments and some, like the snake one, don't work at all. The one I'd go with in an actual moc is the first design I came up with, 8.
Okay, so I just tested a real version of 8. It works great, you just need to remove the 1x1 round tile with bar and just insert the wrench itself into the shell. Cool, that worked out nicely.