This is the lower part of a "Gozinta Box" - a magical illusion developed by Lubor Fiedler.
Though the illusion is self-working (if you know the twist) it is the patter and presentation that creates the magic.

Basically you have to print both the upper part and the bottom with the utmost precision in two different colors - thus creating two (besides their color) identical boxes.

I think that all of you who searched for gozinta boxes already know what to do and what to expect.
The size is approx. 10cm/4" with a wall-thickness of 1mm - the outer dimensions of the bottom are 0.5mm smaller.

Have fun in memory of Lubor Fiedler - I'm sure he'd appreciate it...

Anycubic i3 Mega

Doesn't Matter

No

not really necessary

With these boxes precision printing (esp. dimensional accuracy) is mandatory.
I don't think that the print settings themselves are the key, but correct calibration of your printer is the most promising prerequisite.