Most decorative Blocks in Fortresscraft Evolved are built by using Construction Paste and can be crafting in the Self Crafting menu.
|Construction Paste Grinder||This machine will turn most natural Blocks into Construction Paste which is used to craft most Aesthetic Blocks in the game.|
Keep in mind that breaking any aesthetic block - regardless its cost - will only get you a single block of construction paste back.
Automatic Placement Edit
Any Aesthetic Block that is placed in your Hotbar can be placed immediately as long as you have enough Contruction Paste in your inventory. No room in your Hotbar either? Use the Middle Mouse button to "copy" any decorative Block and continue building with it.