good tip...don't try to scratch waterbased paints with yer nail straight away
waterbased dry outside to in so may look dry but isn't. paint the shell.. let dry for a day or two. preferebly on a low heater if poss. then, seal your shell and let that sit overnight or for a couple hours if over a heater.
as with anything, the more time that passes, the harder/more durable it gets but when on a relatively tight deadline do as above and you should be ok.