Here's a simple solution for displaying cards in your hobby room and it will work on any smooth vertical surface, including cupboards, doors, windows and walls. I had four plain hutch doors above my work area and mounted eight rulers; in all, I can display up to sixteen cards.
For this project, the supplies needed are acrylic rulers and 3M Command mounting strips (removable double-stick foam strips). I cut the Command strips lengthwise, and mounted the rulers with one half on each end. In the center of the vertical rulers, I added an additional half strip so the top card wouldn't slide down. Voila!