Attached is a makeshift foot harness I used for suspending my feet in mid-air during diaper play (waiting for the glycerin supposetory to reach full effect).
It is just rope criss-crossed between headboard posts and my ankles. I put non-adjustable loops on the ends to make the road easily removable from my high heels and the post of the bed. The ropes should be tied together where they intersect (you could also use four ropes and have a metal ring where they intercept). If you don't like the results, you can add a spreader bar (wood dowel rod) with ankle straps at each end.
P.S.: The diaper play was very sexy by having my high heels suspended in mid-air and I had a relaxing time laying on my side after I took the ropes off after going in my diaper.