Further spoilers for MTG: Unstable Show more
Now I'm genuinely curious! Contraptions have "no border"... so I'm presuming they are going to have a non-standard back - which means they likely won't be shuffled into your deck.
This makes me think that maybe contraptions will be used as something like a Yu-Gi-Oh "fusion deck" (tokenish, but you must have the card in your possession to actually use it?). #mtg