Light tents are great for creating low contrast lighting for small subjects.
With several lights aimed at the outside surfaces of the light tent, the light inside becomes low contrast because it's coming from many directions.
Light tents are a must if you're photographing highly reflective subjects such as jewelry.
If light is not reflecting back to the camera from the surface of the subject, the subject turns black.
Place your subject inside the tent.
You can float the subject above the surface with concealed supports.
The surface can be a sweep of paper that runs from below the subject back, and up, the rear of the tent.
You can also use Plexiglass, fabric, or ?
If the subject is reflective, use a surface that has a similar value as the subject.
For example, if you're photographing a vase with a black glaze, a white surface would create a bright white reflection on your vase.
A dark surface will create a less distracting reflection.
You can use the rear panel of the tent as the background.
You can make the panel white, or various shades of gray.
Move the rear light closer for white, and further away for gray.
Place several lights on the outside the tent, shining on the tent.
You need some dark areas on the surface of your subject to show its volume and shape.
You can block light, to create dark areas, with a flag.
That's a piece of black paper on the outside of the tent.
Go to A Cheap, Bright Light.
Poke the camera lens through the small opening in the tent.
You can make a tent from white, translucent, fabric or plastic.
You can use 1" PVC pipe to support the fabric or plastic.
Cut the pipe with a hacksaw or a PVC pipe cutter.
You can also use a lamp shade, white plastic trash basket, foldable laundry hamper, or ?
Here are some tutorials.
Light Box/Light Tent - Bill Huber Using PVC pipe
E-Z Cube Light Tent Also tutorials
Lastolite ephotomaker and other models