(apologies for the picture quality in this section, we started this project a little too late in the afternoon for good natural light...)
The next step is to make the second layer of screen. This layer will go on top of the soil and contain it from the top. Cut a piece of screen about two inches bigger than your box in both directions. Fold one inch over on each side so that you have a box-like shape. Make sure that it fits inside of the box. It shouldn't fit over it like a lid, but in it. The folded over edges will fit in between the soil and the sides of the box. Set the screen aside for now.
Mix a batch of potting soil into the box. We couldn't find a cactus or succulent mix, but you can make your own, either with sand or perlite/vermiculite. This also helps with drainage, it prevents the soil from getting compacted. I have a feeling that perlite or vermiculite is a better choice for this project because I suspect that sand might fall through the screen. Don't put too much soil in the box, maybe about half as much as you think you'll need. The plugs will displace a good deal and you don't want the soil to overflow.
Now that you have the soil in, start arranging your succulents. I started out having them on a grid, but later made the placement a little more random. Flora's are very grid-like, which works very nicely, but at this scale random worked better. Just set them on top of the soil, you'll be moving them before they get planted.
The next step is to take your screen top and set it gently over your succulents. Using a sharpie, mark circles over each plant. Once you have it all marked, use wire snips or heavy kitchen shears (no fabric scissors!) to cut an "x" in each circle. Remember you can always make the hole bigger, but not smaller. Fold the flaps down so that you have a semi-smooth opening. You'll want the plugs to fit pretty snuggly in these holes, too big and dirt (and possible the whole plant) will fall out if you hang it up.
Once all the holes are made, take all the plants out, and set them aside arranged in approximately the same way so that you'll be able to get them back in the right arrangement. Slide the screen into the box, making sure that you have soil contained in the flaps on the sides. I pinched a little lip and stapled the screen to the sides, just for added protection. With you finger, start digging holes in the soil and setting the plugs in. The top of the plug should fit just under the screen, you can use adjacent holes to push the soil in around it. Make any holes bigger that need to be, and try to keep the soil under screen as much as possible.
...the finishing touches and the final product in the next post...