Hi! So it took me some time to find the material (i had no idea where to search), and i had to use a box and cut it up, instead of that color..thing you mentioned, but here it is! Finally Sheldon has a proper playpen... now he is totally spoiled.
I will post this thing in another forum and put all the credits you put, i hope its ok
Here are the pics:
Thanks so much from Sheldon and me!