As Erich mentioned in his post, the Omega Art Series was offered in (3) different
sizes and with art inserts on the back by various artists. Erich showed the largest
(maxi - 40mm) size in the Emilio Tadini 1987 version. Here is an example of the Max
Bill model in the maxi size: 


And here is a picture of the original box, manuals and spare integrated leather straps
that came with the watch:
And an Extract from the Omega Archives:
Here is another watch from the Omega Art Series: the Richard Paul Lohse model in the
midi (32mm) size:




A picture of the inside caseback, showing the attachment of the integrated leather
band:
Finally, here is an example of the lady's "mini" (22.3mm) size Omega Art Series watch. (I forget which model this is):

An interesting point to note: the lady's mini models do not have the limited edition
numbering or artist signature on the back and appear to not be included in the limited
edition count of 999 pieces issued of each artist version: 
The 3 different sized models used 3 different Omega Quartz movements, with the maxi
using the Omega caliber 1433 (no pix, sorry)
the midi size used the Omega caliber 1436 (ETA :
and the mini size used the Omega caliber 1455:
I'm not usually much of a quartz watch fan, but the beautiful black sapphire cases and clean minimalist design on these watches made them an attraction for me.
Similar to the Omega Art Series, was the Omega Deville Symbol Series (shown below),
but I'll just show a few quick shots and leave the in-depth examination for another day:






Best,
Greg