@FishW Hmmm im assuming you used like pistons with the hay bales thing, and then the top has dispensers but that leaves a few unanswered questions.
Another option is that you somehow get into a bedrock hole and trap them.

Sorry for going off topic, but this brings up a question: @Nysic @Blackened_Dawn (because I think these admins are active on the forums) Are we allowed to make holes in the overworld that go into the void?