LSynth is a tool which allows you to add complicated flexible
hoses, bands, chains, and treads to the LDraw files you make with
If you've ever tried using LSynth on another platform, you have a pleasant surprise awaiting you. With LSynth in Bricksmith, there are no configuration files to edit, no extra programs to run, and best yet, you can edit your flexible objects live with your mouse, and go back and change them whenever you please.
None! LSynth is integrated directly into Bricksmith. You already have it!
Insert an LSynth element into your model by choosing Model > Insert LSynth Flexible Element > Hose (or Band)
Your new object will appear in the File Contents outline, but you won't actually anything yet. That's because you have no constraints in you object to give it length and shape.
Insert constraints by choosing Model > Insert LSynth Flexible Element > Hose Constraint (or Band Constraint)
Constraints will appear immediately, but they are very small. Don't overlook them!
Drag the constraints around. The flexible object will appear before your eyes.
LSynth is a very rich tool. You can learn a lot about it by downloading and studying the example files here. Note that you only need to download the files with "Constraints" in the name; Bricksmith automatically generates the output and needed, and best yet, it's even editable.
There is also some general conceptual information here, but it is mixed in with a lot of painful Windows setup instructions you don't have to worry about!
The official website of the LSynth engine is here.