Have you read the clock case article that has recently been in ME.
Also watch the oak, the tannins can encourage corrosion and lead rot.
Toughened is sometimes costly in thin sheets and the weight will soon go up if you use say 6mm, 3mm or picture glass will likely be OK for big cases I have used sheet polycarbonate.
This one is 12" high and uses 2mm picture glass

And this about 5ft square and polycarb

J
Edited By JasonB on 22/11/2012 18:46:20