Minimized heavy duty printable filament spool

The concept is based on the "Heavy duty printable filament spool", but I re-modelled everything from scratch.

The problem with the source one is that -

* the dovetail keeps breaking. I recount I actually had 3 arms broke at the same point. So I made it bigger, much bigger. And adding a flap so that pressure could be relieved that side too.
* The holder arm is oversized. I reduced it to almost half of it, and it still overly hard for the job. The length is cut of a bit because of the new