Instead of the decon planner, or any other item, which in theory could be on the belt, how about using the filter=cut-paste-tool? Uses the same built-in icon as the cut tool on the toolbar. It is an "item" in the game and available using all the same methods as the planner, or an iron gear wheel. It will copy/paste like normal as well as being copied with the settings copy process of Shift+RMB -> Shift+LMB. It reproduces faithfully when copied into a larger blueprint. The scissors seems like a better look than a colored square.