Huge subject you've delved into. Terrarium comes from terra = earth. So the subjects in terrariums are primarily earth-related which means plants. Vivariums are for terrestial animals - frogs, serpents, etc. Orchidariums are terrariums that contain, mainly, orchids. I guess there could also be 'ariums for insectivorous species, etc.
As to where to get one... several folks here have had their own made for them to their own specifications. Others have adapted aquariums (get it, aqua is water!) for their needs. I have done both. If you choose to go the custom route (a good way to go in my opinion) then Paul at
First Class Aquatics LLC - Custom Acrylic Aquariums, Vivariums and other reef related equipment. is the best recommendation I can give. I spent a long time (months) deciding on how to spend my money and getting his input (which is first class, by the way.) See my gallery at
http://www.orchidboard.com/community...ry.php?cat=608 Have fun in your project.
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Ross
http://orchids-ross.blogspot.com/
I don't do most Dendros or large, "floofy orchids". For me it's minis (like Angraecoides), Masdies, Paphs, and others that crept in somewhere along the line. See my orchid list for complete collection (usually not current.)