I have decided to do a simplified version for a present, set inside a Stargate, many of the features previously mentioned will be disabled for simplicity.... feature list will be: 

 - time display

 - switchable colour modes

 - variable brightness

 - simple 3 button configuration (colour cycle, hour increment and minute increment)

 - variable brightness will be via LDR, with a switch to change to a pot for manual setting

 - 'dialing' effect for the hour and min light blocks every hour (or maybe a generic dialing effect)

preliminary pics:

 ^ the cut parts with preliminary graphics ^ loosely assembled

 ^ LED ring and final graphics

the ring assembly will be sprayed mat grey, printed graphics applied, touched up where needed and varnished (polypropylene spray probably), this will then have the LED ring set into it and wired up, then I will work out how to make a (hollow) base/ramp to house the control gear.