Can you produce a Faraday Cage with no holes in it? In a Faraday Cage, I've seen that often people tend to "limit" the size of the holes to help shield against radiation of a particular wave-length. But what I wanted to know is - "could you not use a material with no holes in it?"
Is it difficult to obtain a material with no holes in it or is there some other obstacle I'm unaware of?
Thanks
 A: 
Is it difficult to obtain a material with no holes in it

No, of course not. Aluminum foil and copper sheets are readily available materials with no holes in them. Of course if you build a "cage" out of these materials and truly want no holes in it, you have to be careful how you seal the seams where the material is joined.

or is there some other obstacle I'm unaware of?

Usually you have some other operational requirements that requires holes.
For example, on the door of a microwave oven you want visible light to be able to pass through so that the user can observe the food as it cooks.
If you're building a Faraday cage for EMC testing of electronic products you want to be able to pass cables through the cage in order to power the device under test and to convey the received signal from the antenna (used to detect emissions from the product) out of the cage to measurement equipment.
If you're building the enclosure of some electronic device, you may need to provide holes to allow air flow through the enclosure to keep the internal parts from over-heating.
Using a material with holes may also be less expensive than using one without holes, simply because less material is required to build the one with holes.
A: 
But what I wanted to know is - "could you not use a material with no holes in it?"

Yes, you could not use a materials with no holes in it. Or, without the double negative, you could use a material with holes in it. Or, more to your point, you could use a material with no holes in it.
But if there are no holes then you might not call it a "cage." Rather, you might call it a "box" or a "bag."
There are plenty of consumer products called "faraday bags" that you can buy and put your cell phone in to try and shield the radiation. You can often velco the bags shut and some even have a nice transparent window you can use to look at your poor lonely cell phone.
