and I haven't even left them out there very long yet. But I'm a worrier when it comes to my animals, so I feel like it would just be my luck that something would happen if I didn't lock the torts up when I'm not directly supervising.
I'm actually suprised how well my outdoor enclosure (made from 2"x12" boards) held up over this past winter. I didn't even take the lid off for the winter, and I was surprised that the wire fencing held up to the two feet of snow it had to bear at some points.
Here's my idea so far for the next pen (thanks to your help):
Start out by digging into the ground about a foot or so, for a little over a 4'x12' space. Build a 4' wide, 12' long, 4' tall "corral" out of those deck planks (probably with 4x4's in the corners and the middle of the 12' sections), and drop that into place. Then put wire fencing down first covering the whole ground area (probably not necessary, but I have a lot of it hanging around), followed by some flat patio blocks to cover most of the area , with gravel filling in the cracks, so I'm left with just about as much protection from escapes/small predators digging in as if I just made a concrete foundation for it, but with much better drainage, and more easily removed if necessary.
Before putting dirt and such in the pen, I would build the lid for it. If I can find a way to make it work, I would really like to make a lid using steel tubing for the frame and 'tennis fencing' type chain link fence (basically chain link fence with small openings), basically just to keep things out as opposed to in. I have a pretty good idea of how I could make it work, but money is also a factor. If it seems like too much trouble I'll probably just make another wood-framed wire mesh lid like I did for the current pen.
Then I'd just have to fill it up with like 18" of dirt, plant it, install all of the hiding areas/water basin and put the torts in.
The only reason I'm shying away from doing this though is that it's a costly design, and I will probably be moving away sometime in the next 4-5 years. It's probably worth it just for those years though. Plus, as you said, it's a design that could be taken apart and moved if necessary.
Thanks for the input. Let me know what you think of this design idea.