This is a remix of Richard Stallard's original design.
When actually mounted to the layout the snap clips had no space to flex and therefore installing and removing the Tortoise was very difficult and could result in breakage of the clips. By lifting the tab clips above the mounting surgace (by making the base thicker) the clips can now flex much more easily.
These tabs are now printing above the Print platform and do require "support" when printing. I would recommend minimal support (10%) to easy breaking off the support.
Typical Printing with a .4mm nozzle should work just fine as there is nothing complex on this print except the support needed under the tabs.

See Richard's original instructions for suggested printing and use.
https://www.thingiverse.com/thing:372972