Press the thingy that looks like a stamp, Drag it over what you want to copy and let go, Then hold the stamp thingy down until it turns white and let go to view your stamps, click the stamp you want to use and tap again to paste it!
Ctrl K to view all your stamps
And Ctrl V to load last stamp
Then drag your cursor over what you want to copy then let go
thanks man ur so big heart person, but can i ask u how i place that in maps? imma new in powder toy thats a little bit oubvius so how u do that? could u tell me in my neutrons nuke map?