Some accessories need some sticky, non-staining adhesive to help accessories stick to figures in gravity defying ways. Through a lot of research, this wax works very well compared to sticky tack/blu tac, and is the same type of wax that sleight of hand magicians use to levitate small objects. If you have ordered certain products from this website, you may have received a small cube to try out.
This one inch square piece of wax will be plenty to help utilize your accessory in the way you want and can be reused again and again. It has many other uses, such as helping your figures maintain difficult poses for balance, just put a blob under the foot and you can achieve difficult poses done by the experts.
While it doesn't leave stain or residue on plastic, avoid using it on soft goods where it will smear.