Three wool buttons on the lid = the frequency (16×16×16 options). Click a button with dye or wool to colour it.
All ender chests with the same colours share their inventory — anywhere on the server.
Diamond on the latch (front): personal — only your chests with these colours share it, others can't open it. Sneak-right-click the latch with an empty hand to make it public again (diamond back).
Pipes and hoppers work.
