Hi Linda,

> My question: what's the best way to draw a pipe with a
> wall thickness?

One way is to first construct a completely solid pipe by drawing a path curve and a circle a distance away from the path and using the Sweep command. Then you can give it wall thickness by selecting the end caps and using the Shell command.

Some more info on these commands here:
http://moi3d.com/2.0/docs/moi_command_reference7.htm#sweep
http://moi3d.com/2.0/docs/moi_command_reference7.htm#shell


There is also a special "Pipe" plug-in that makes it a bit easier to create this kind of pipe object, that's a new command that you download and copy into the \commands sub-folder to make a new Pipe command available, some more info on that here:
http://kyticka.webzdarma.cz/3d/moi/#Pipe

- Michael