Visible Barriers
This mod becomes an indispensable assistant for map creators and those who test them. With its help, barrier blocks become visible as full-fledged solid blocks - just press a hotkey (default: B).
In addition to the main function, the mod offers a whole arsenal of useful tools for map building. You'll have access to a separate tab in creative mode with hidden blocks, commands for mass infection and object locking, and the ability to see marker entities.