You mean the enclosure like cabinet rack? or are you talking about casing to cover it over?
Antminer itself now has the cover
if you are into rack, you can use standard rack with shelvings and you can dense them really well without worry about damaging the hashing cards or the control card as S3's components are now completely covered in the retail metal casing.
If you are planning to use the enclosed rack cabinet, you might want to make sure you can push/freshout the hot air from ants. I'm sure S3 will be the space heater like S1.
P.S: The photo came from CoinDesk.com -
http://www.coindesk.com/bitmain-releases-energy-efficient-478ghs-antminer-s3/I'm browsing around just ordered 10 of the S3's and looking for a enclosure for em anyone got any good ideas ?