I built a set out of an old (cheap) particle board headboard.. Cut the holes, and used a "noodle" - those pool tubes made of closed-cell foam - to cushion the holes. I just cut them to length, slit them longways and then glued the to the edges of the cutout holes. Of course, I tacked black fake leather over them to finish the look.
I have been on both sides of them, and you are definitely helpless. Mine had toe ties too.
What I really enjoyed doing - if I was only tickling her feet - was to not secure her wrists. She couldn't get at the latches or me, and it's great fun to watch her flop around and flail, and her feet wouldn't move an inch.