Arm protector for Mark4

Inspired by [GepRC Mark 4 - Arm Guard](https://www.thingiverse.com/thing:4272304) and [GEPRC Mark4 Arms Protector](https://www.thingiverse.com/thing:4936552), but has no holes for bolts. The idea is that the arm protector is printed with TPU plastic and is glued to the arm.

The protector arm fits OK 5″ Mark4 frame arm, but with 7″ frame is was a bit tight.