My first coach's card was done about two years ago, picturing Bill Mazeroski as a Seattle Mariners coach.
I've just completed by second such card: Rocky Colavito as a Cleveland Indians coach on a 1978 Topps-style card.
I have publicly thank here a fellow custom card maker, Keith Conforti, who when he saw the beta version of my card on forum, suggested I go with the horizontal "As Player/As Manager" format that was used for manager cards that years. That idea had never crossed my mind. I like it so much better than the standard '78 style.