Optifine cape editor ERROR | Hypixel - Minecraft Server and Maps
How To Get An Optifine Cape in Minecraft! - YouTube
How to Get a Cape in Minecraft
How To Make A Custom Banner Optifine Cape - YouTube
FAQ - OptiFine documentation
If you were not aware & using optifine, you can donate and get a cape which appears only while optifine is being used, but I think is totally worth it : r/Minecraft