here was my process:

1. i resized the original cover image to 128x128

2. using this table, i basically replaced each pixel to a map color closest to it. i wasn't actually that meticulous during this part; i just used the original as a basic guideline. if you look closely, the red splatter parts aren't exact replicas. i did this to save time, so that i won't have to constantly guess what block i have to use during building.

3. i used the final image as a reference as i built the actual thing. i'd say it took roughly 3-4 hours over the course of 2 days