This is really an idea by @silver turtle "'honestly a magical one-way barrier would be perfect for many uses...'" that I picked up and ran away with.
#1298949560659345488 message
⬆️ Blue is always one way. Arrow shows which way, Direction can be changed with switches.
🟢 Green is passable either way.
🟥 Red is impassable.
Barrier colors can be changed with switches.
They could be drawn to line or square sizes like blocks, and would be animated with the arrows and color vision deficiency-assist shapes flowing over them.
While many of these same passage controls can be implemented in other ways, a full set of Magic Barriers would offer specific presentation differences for player interpretation in regards to puzzles and etc...