I assume you're referring to a Solid State Drive or Solid State Hybrid drive?
Any external enclosure you wish to make yourself will suffice assuming you have the connections needed to allow it to communicate back to the computer.
When you buy an external pre-made enclosure, it would come with a controller board that offers one of the following connection types listed below. You can technically run a standard sata cable to the hard drive directly but you would need an external power supply. Fry's Electronics sells them. You could also look on newegg or amazon.
Typical external connections types are going to be either eSata, USB, or Firewire based.
Out of those, the fastest is eSata. This does assume however that you have an eSata port on the the computer to connect to. If not, Firewire 800 or USB3.0
As far as the enclosure goes, adding some type of active fan would help with any heat coming off of the hard drive itself. It depends on what you'll be using it for but, just a suggestion.
As an example, something like this would work: