here's a wall of custom heads i've put together, you can add you're friends to it as well,make sure you use the the redstone setup at the back to obtain their head, just put this command: /give @p skull 1 3 {SkullOwner:"username"} . replace "username" (keeping the " ") with whatever you're or you're friends username is, there should be a few spare command blocks with the command in it, if its not there then put it in, make sure you put their username in correctly (case senseitive)

Also make sure you are using a snapshot (Latest one is prefered) otherwise command blocks won't work

Make sure to credit me, if you use this in a map. Also if a Youtuber changes their Minecraft username (or In game name as some prefer to call it), i will edit the command blocks so that you can still obtain the head.