I've always been curious as to how it feels to be restrained facing the ground like they do in several Bleu Fetish videos, that has always intrigued me as an interesting twist to my usual favorite way of being tied, spread-eagle. Having one's abdomen raised by pillows or other wadded up fabrics always helps immobilize more, and perhaps having more ropes added to make it so you can't move your arms or legs (Haha, maybe like that table used by RealTickling with all the ropes threaded through it). One thing of interest is maybe have something like a human sized piece of foam with an indention cut to a person's size and the position you wanted them in, that way when in it and somehow made so that they couldn't get out (more rope I guess) at least their front end would be open to tickling, though this cuts out the back and sides, sort of the idea of a vac bed, though that might be another good way to completely immobilize.