Are there water sinks? Or invisible background wall to cointain it?

I want to make something like a waterfall, so that's my question. If anyone knows a way, let me know :)

The idea is to have something like in this video. You need to be able move across it, so an invisible bedrock wouldn't work.
http://youtu.be/8RywyLbNk10?t=5m42s

PD: Is rubble gone? I loved rubble... any replacement? (a soft wall that anyone can destroy without effort) :(

 

Make a new block similar to bedrock but no sprite?

 

Yeah, I thought about that, but the problem is that you wouldn't be able to move across it :\ I'll update the post to reflect that.

 

Using doors allows you to pass, but will not allow you to place blocks.

 

With some minor modifications (I think) that would be the best choice, thanks!

 

or maybe enemy trapblocks?

EDIT: make a separate team with their own trapblocks,
and use those. don't include the team in the game, but use their trapblocks.
No one can touch them then.