Using DraftSight V1R3 Beta

I'm fairly new to CAD, although I did play around with AutoCAD some years ago.

The 3D command gives me some standard shapes I can create. So far, I have been able to use 3D boxes for my project (drawing a frame made of 1" rectangular tubing). I was able to draw a plate 4"x4"x1/8" thick using the 3D box command. But I would like to create a 3D triangular plate 1/8" thick, or some other arbitrary shape, with thickness.

Can anyone point me in the right direction? Google searches haven't turned up much.

Thanks

Larry Bradley

Ottawa, Canada