I'm working on a new 2 x 4 tile design (7" x 14") that will fit into the bottom of an 8.5" x 15" tray. I started by laying out eight tiles face down, arranging them in a 2 x 4 configuration, and then using small pieces of tape to hold them together temporarily. I then turned the whole 2 x 4 piece over and drew a string across all eight tiles. I've drawn three as shown in the image to the left. The string that will organize the upper right tile is barely visible, but you'll see it if you look carefully.
A few months ago, I found a tray at Barnes and Noble with a pre-cut mat for four, 3.5" x 3.5" pictures, exactly the size of Zentangle tiles. I bought the tray and inserted four tiles I'd already drawn -- instant lovely! I put the tray together at first just for the fun of it, but to my surprise, I actually use the thing quite a bit. It's great for carrying several small objects from one room to another, which, for whatever reasons, I seem to have need to do fairly often. Since the tray idea works, I'm making another one, but this time, with a picture frame that only looks like a tray. It won't be quite as strong as the first made-to-be-a-tray tray, but it should work fine. I'll post the tiles for this new ensemble as they unfold.