If you look at most of my threads, you will notice that I hand paint most of my models. I laminated heavy, which helps in maintaining the integrity of the parts. For large projects, ie: Baneblade, I will use regular automotive grey primer using at least three coats of light spray. As you already know, primer is a great base for humbrol, revell, GW citadel and off the shelf acrylic paints in tubes. The Baneblade I made, I handpainted the whole project in water based black acrylics as a base, then I hand painted over that and Olive green. Remember, that the base will dictate how the color is going to be in the long run. Red primer is great for Blood Ravens and Grey for The wolfs. Experiment but be sure the paper is thick enough to withstand the water based colors. One sheet of regular cardstock will warp in parts that are large, while it will hold if the part are small. Experiment and have fun. At least paper is forgiving, make a mistake, print out another sheet or in worse case scenario, start over. Imagine making a mistake with a GW Baneblade, it will cost you a bunch, but a cardstock baneblade, only the irritation of starting over. Enjoy and see you around the forum.