USA Gear Steam Link & Steam Controller Case - Hard Travel Case with Removable Pouches, Accessory Storage for USB & Ethernet Cables, Water Resistant Exterior & Scratch Resistant Interior - Black :
It fits! Steam controller case. : r/Stadia
Amazon: Steam Controller + Carrying Case Only $34.99 (Regularly $69.98)
Accessories Steam Deck | Case Steam Controller | Steam Deck Carrying Case - Hard Cover - Aliexpress
Valve fined US$4 million in Steam Controller patent case - Legal - News - HEXUS.net