you can't
If you don't know a thingabout making add-ons don't try. I have been watching you and you seem like a guy that want to make something that is cool to someone. A printer rocket launcher is so easy and doesn't even require editing the model.
How do I open a .dts file? I need to edit the printer model into a printer rocket launcher
You have no idea what is intentions are. Don't tell him what to do.Just use the default model that Awdax posted the link to.
Ya causeyou have to edit the model to make this. No you don't and he probably doesn't know crap about what he is doing.