I am currently working on my first mod which allows you to place blocks midair. How it will work is when you are flying (using flymod, etc.) by using a command you can place a block directly infront of you even if you arn't placing a block on an existing block. I will try my best to make this plugin use Permissions. This is the first plugin I am making so go easy on me Also if anyone has any good ideas please tell me.
Try something with this function: http://javadoc.lukegb.com/Bukkit/d4...Entity.html#a03e2192e3c89529d1f59ec5ce04370ba
I think it would be nice if you could toogle it by sneaking in the air, i think there's a player.isSneaking() and a world.getHighestBlockAt(...), so this should be no problem.