Foamie question

ok, this may be a stupid question
when I build my Foamie, instead of using PMF, what if I cover all the seams with this Flex Seal Paste they advertise and then just paint the whole thing with several coats of paint?
when I build my Foamie, instead of using PMF, what if I cover all the seams with this Flex Seal Paste they advertise and then just paint the whole thing with several coats of paint?