I (very easily and inexpensively) put together this terrarium for my coffee table.
I started with a large glass container; minus the cover (previously seen here). Then I collected the cacti and succulent plants I had scattered around the house and placed them in the jar. Honestly, I didn't even bother to transplant them. I bought all of these plants about 6-8 months ago at the garden store and they have fared quite well in their original pots.
I added $3 worth of rocks from the Dollar Store to keep the plants steady and disguise the pots and two brass camel place card holders for interest.
I put the whole thing on this round graphic tray I got on clearance at Target a couple of months ago and added a larger brass camel. I love, love, love brass and these have special meaning since they were brought to us years ago from Kuwait by a family member who was living/working there. (I love pieces with history and a story)!
And that is it! I actually find that cacti do better when not in direct sunlight and are watered sparingly; only when the soil is quite dry.