To be fair, concerning her creation of time bombs, we saw Kyoko make a telescope out of her ring/soul gem. We've seen Mami create ribbons out of hers. This seems to be a distinct sort of creation power different than when they "power up" so to speak and go into full magical girl mode with their own unique weapon/power of choice.
It would suggest they have some ability to create objects. Whether it is only one specific object (doubtful; at least I find it highly doubtful that Kyoko's "special" creation ability is to create just a telescope
), or it's just general creation magic, we don't know at this stage.