This is a lid for dodecadron's joycon case found here:
Nintendo Joycon Storage and Transport Case by dodecadron | Download free STL model | Printables.com
Uses a friction fit to not slide off. May make revisions in the future though as of right now is 100% functional.
Print upside down without supports. Used Cura, 0.2 layer height defaults.
Printed in esun PLA
The author marked this model as their own original creation.