The RetroFlag GPi Case, which uses a Raspberry Pi Zero, looks very nice. In this video, MakeUseOf gives it a 9/10 score.
If the idea of making retro game players using Raspberry Pis appeals to you, I invite you to check out a book I co-wrote this year, called Raspberry Pi Retro Gaming: Build Consoles and Arcade Cabinets to Play Your Favorite Classic Games.