good leather cuffs as described earlier with chain works. Use them though with thigh belts and waist belt, locking the cuffs from the wrist and ankles to the the thigh cuffs, small belts to go from the waist belt to the thigh cuffs and its very hard to escape.
A good hogtie with good leather cuffs and very short chain going from right wrist to left ankle and so on. This can be made harder still if you use a waist belt to hook both sets of wrist ankles too, which shorten her ability to move.
not sure that it will work for 3 hours with her being comfortable though. It maybe that she needs some discomfort to stop her from trying so hard to get loose.