Build a 5 by 5 structure ( make sure you have the space ). Fill it and add another layer only on the exterior. Then remove the middle block from the second layer and add the 3rd layer on the exterior.
For a very quick video check the one below:
Timestamps:
00:00 Intro + Grid
00:44 Propelled Achievement
00:55 Now that's inspiring, Who goes there Achievements
01:16 Captain Achievement
01:29 The Gardener, Sculptor Achievements
02:14 Architect Achievement
02:30 Every block matters, Opulence Achievements
02:56 Rome wasn't built in a block Achievement