MASS-HDD bay compatible with QNAS backplane

The MASS-Free case design is excellent, but it's a pity that the HDD bay cannot adapt to the backplane, so I created this HDD bottom bay that adapts to the backplane.

I had a terrible experience the first time I printed the MASSFREE HDD bay. To be honest, the support optimization was very poor, which was quite frustrating.

Therefore, I modified and optimized the HDD bottom bay model.

The HDD bay V2 version is compatible with the Interstellar Snail Type B backplane.

The bottom accommodates fan sizes 12015 or 14015. I removed support for the 25cm fan because the bridge for the fan slot was too fragile and would break easily, so it had to be reinforced.

I re-optimized the support for the hole layout, and now printing consumes significantly less support material.

Of course, I was too lazy to make the fan cover for the base, so I'll leave it for someone else to complete.

Also, I discarded the base because my own tests showed it wasn't stable; it's better to place the HDD bay directly on the surface.

This HDD bay design is not for commercial use, I hereby declare.