>>33331153He can sleep in his ball, but usually he prefers to sleep on his torn up section of couch where he also sits sometimes. He could get a chainmail hammock to sleep in but Ignace's room is a bit of a whirlwind of crap right now so it's not feasible.
Here's a bonus: his chair at both Ignace's and Ricard's place has an elevated back to accommodate his blades - the back of the chair is placed where his shoulders can lean against it instead of his back.