2 liter plastic box with tight-fitting lid (Tupperware style) with lots of small holes (pin sized) in lid.
Invert over two short bars halfway down the body of the hive on the empty side of the follower.
1" hole near the bottom of the follower so the bees can access it.
You can also space two bars apart with 8mm shims, leaving a gap in the middle and place a standard Miller feeder on top. You need space in your roof to accommodate this, obviously.
Avoid entrance feeders and tanks that can drown bees.