Updated My Daughter's Pedalboard After Tone Studio Update : r/BossKatana
Amazon.com: Boss GA-FC EX Foot Controller for BOSS Katana Amplifiers : Musical Instruments
BOSS GA-FC Guitar Combo Foot Controller | Musician's Friend
Boss GA-FC Foot Controller | Sweetwater
Haven't seen a lot of examples of boards that implement the GA-FC, so here's the one I just put together! (Also posted in r/guitarpedals) : r/BossKatana