Seamful (For 1.21.6)

Seamful is a resource pack that alters Minecraft's blocks so they do not tile perfectly by giving them noticeable edges, whether it be used for counting blocks on builds or simply as an accessibility tool! Seamful aims to remain unobtrusive and stick to the vanilla look, and does not alter anything but the general outlines of blocks. 

 This pack DOES NOT require Optifine.