Location and tutorial of Sandbox Skull and the rest of the Mythic Map Skulls. Sandbox, Assembly and Orbital. Orbital and Assembly are Pretty easy. Sandbox on the other hand takes a little work.
I included a tutorial in this video to show How I was able to claim the Skull. I'm sure there may be different ways of getting to it, but this was mine.
I hope this helps.
Sorry if I spoiled this for anyone, but you were warned.
If you're just lazy and dont like a fun challenge, here is a link to a map to get the Sandbox skull.
"Spawn at the Skull, Get The Achievement, Move On With Your Life"
http://www.bungie.net/Online/Halo3UserContentDetails.aspx?h3fileid=68956613
