Weaving on a single unit drawloom gives you ultimate control of each individual unit, and is most commonly used to make beautiful free-form designs in damask. Anything you can design on graph paper can be woven with this kind of attachment. As far as contraptions go, this is the simplest and most economical drawloom attachment to set up and use.
For detailed setup instructions and an excellent reference, see Becky's DVD Dress Your Swedish Drawloom.
Please do also be tempted to check out our Drawloom Basics class and our Drawloom Treasures weeks to gain personal experience and try each kind of drawloom out for yourself.