The tree frog design from the Mitsui website (commissioned from the Kei Craft paper craft studio) was the most enclosed model I'd tried yet, because it doesn't have lift-off or pull-down access to a secret compartment. I actually had to alter the design a bit to give me more access to the inside while I was making it. So, my version of the frog has an open mouth and while I was working on it I had a hole open at the other end, where I would later slot in the legs before closing up the whole area. I also experimented with making the legs a bit more 3D, as in the original they're just flat. For the front pair of legs, I added some felt behind the leg and then embroidered from the outside. I think they're a bit chunky and it wasn't as easy to control the stitching like that. For the back pair of legs, I made a mirror image copy of the existing legs and, when it was fully embroidered, attached the two pairs of legs together, filling the space between them with a bit of stuffing where appropriate.
The frog is made from thick interfacing, apart from the feet, which are on medium interfacing which I left unembroidered in places, because I felt it looked like the kind of webbing frogs have.