Amicchan
Forge Microblocks (or Forge Multipart), and in later versions, Chisel and Bits are very useful mods for resource efficiency; they reduce the amount of air filled. Unfortunately I don't see many posts that highlight this usage.
A commonly cited example is glowstone nooks; microblocks' glowstone still produces light, so cutting glowstone into nooks increases the amount of effective glowstone for the same light that glowstone produces. (A bonus specific to environmine is that glowstone does not produce heat like torches.)
In my Crash Landing world, I used Forge Microblocks to prevent tiny and giant spiders from climbing over the base wall. I used way less cobblestone than if I used only the cobblestone block
In my cactus farm; I used Microblocks to compactly automate the breaking of cactus.
I love microblock mods.