What are those pieces of wood you used? Also how high is it and how did you put those round prices together? I'm just wondering because I'm about to build an outside enclosure for my box turtle and I like this design.
The main enclosure is 8 foot landscaping timbers, Lowes and Home Depot sell them for about $3 each. The top cap is 1x6 to provide a lip so they can't climb over. Height is about 1.5 feet. Cost just under $200 with the other materials for the lid (wood, mesh, hinges and latches.
I split the covers in half to make them easier to lift. Haven't put them on but they look like this
As far as the landscape timbers, if you leave them 8 feet long and do an 8x8 enclosure you shouldn't have to cut them. Just bury the first row at least halfway in the ground and then stack them like the old Lincoln Logs, alternating overlaps on the corners.
Each row is screwed to the one below it by 4" decking screws, 1 at each corner and two in between. Alternatively you can use 2x4s in the corners to anchor it but two of us had trouble moving it at 2 rows high, it's not moving at 4 rows.
And I've only seen them sold in 8 foot sections. For 12 foot you could do 1x8s in 12 foot sections then just secure them to buried 2x4 or 4x4s I'm the corners and one every 3 feet.
I used the same timbers for my box turtle enclosures. I connected the bottom three by drilling holes all the way through by either end and then driving a 24" rebar through and deep into the ground. The top piece was connected using the 4" deck screw.
That was my original plan as that's how I built my raised planter beds at my cabin in Tennessee so I didn't have to dig into that damn clay. With 4 rows plus the lid, it's not moving.