Hexapod Thigh Bottom Remix

**This is a remix of Hexapod v2.1 by smallptsai.**

This remix makes the leg assembly simpler and more robust by moving the leg screws from the side to the top. This makes the legs much easier to assemble and disassemble, and avoids the fragile side screw points from the original design.

The remix includes three parts: a redesigned `thigh_bottom`, a reused `body_top` provided as `body_bottom` and a `bottom_plate` to cover the large hole in the reused body part.

The redesigned `thigh_bottom` does need a small amount of print support, but overall this improves the build experience and makes the hexapod easier to maintain.

**Required Printed Parts**

Print the parts from the original model as usual, with the following change:

- Print the redesigned `thigh_bottom` from this remix
- Print `body_bottom.stl` from this remix instead of the original `body_bottom`
- Print `bottom_plate.stl` from this remix
- Print the remaining original hexapod parts as needed

**Included Files**

* `thigh_b