I'm almost done with a complete remodel of my hobby room and I found the bricks I was looking for. They're called MAGIC BRIK. No "c' in brick. You paint the base surface the color you want the mortar to be, lay down the mask, mix the dry powder "bricks". and spread it evenly over the mask. When dry, you peel the mask and there's your bricks with the mortat joint. I've used the stuff to create a scale version of the Veterans memorial we built in Winfield, IL.
The stuff was wonderful and I think I'll order a batch. There are several suppliers online.