Cutting tube joints.

Hi,

I am contemplating a project which will consist of a triangulated space frame made from 100mm Steel tube, with a 3mm wall. (4" x 1/8")

How are the splices where tubes meet other tubes at angle actually cut in production ? Presumably one uses a Plasma cutter or oxy-torch, but do you make cutting templates and mark the tube, or is there a clever wrinkle ?

Thanks for tips and suggestions.

Steve