And to all the naysayers, the OP is brand new to BYC, how about a welcome instead of an attack? There are threads about keeping indoor chickens, after all.
Welcome to BYC! It looks like your chickens are bantams, which might make it easier to keep them indoors. And people DO keep chickens indoors, including roosters, don’t let everyone rain on your parade. Your idea might work out, tho you cannot stop any animal from becoming an adult. I...