The main thing is I'd make it primarily a body suit (It would be a bodysuit, shoes guantlets, elbow pads, gloves and hood). I wouldn't actually make that beige turtle shell looking bit completely out of foam because that would make it harder to move in but you could use 2mm craft foam wrapped in the fabric instead and glue that to the bodysuit in place of sewing that on. It'd still be part of that 3rd layer though. If you were to make it out of covered foam then don't extend the top of the front all the way to the shoulders, just make it long enough to sit under the hood. That way there is some stretch still available in the shoulder area for if you stretch yourself out. Sitting could also be problematic, you could probably do it but you might pop a glue seam. For the beige lines on that bottom layer I'd really consider getting fabric printed at spoonflower with the proper designs, they do stretch. You could paint them on but lemme tell you that's gonna be a couple days of your time and at least a full day of someone else's since you have to wear the bodysuit while painting it. Neoopaque paints from dharma trading work really well on stretch fabrics. And I think that's it.