There's no need to hold it in your hand. Place it on a flat surface and frost it.
I'm not sure what you mean about move around the plate. If you put them on a rack and cover with poured fondant, you can move them when they have set up, decorate, etc and place for final look using a spatula. Or "glue down" with frosting to cardboard 2" squares which can be double taped to your work surface, ice, decorate and move into place with a spatula. Is this any help?
I made some out of fondant and put letters on them. Worked great!