It was a great idea my mom actually came up with, I took these with my phone when she was alive and kicking.
I had her in a small tank at first,
That was her critter carrier, I kept her in there for a little bit until she became more adventurous, then my mom and I worked on this together
We tapped the sides down so she couldn't get stuck, it took a while but we did that and she loved it.
Also for the climber in them, I left her a couple branches without sharp edges and took some old toilet paper rolls and cut them in half.
Like that, I covered one in the napkins so it was comfy for her. If they get stuck at all they figure out to shift their weight and they can get off of it easily.
Also mist the napkins so there's texture for your little one to crawl on, easier for them to move around.
Edit:
Also whenever I had some extra time I'd take a napkin out and open it up so it'd make a huge square. She'd walk around and climb on little things for a bit.