This is a case with Joy-Con rails .I have printed this with PETG altough I would recommend hard TPU or NYLON if you print with PETG cut two of the corners a little .And I would suggest partially melting the sides of the rails to make it fit and insert it repeatedly .It was just a fast project to make a steering wheel . 

Use with https://www.printables.com/model/512721-steering-wheel-controllerphone-mount-for-racing-ga and https://github.com/danielwitkowsk/DroidWheel_releases .