We had to do one way back last year as part of our development of ideas and research. it was basically to prove to the teacher some of us had actually done something.
it was hardly a "speech" as what you're making it out to be. we just had to talk to the class about what we we're going to build (including sketches/technical drawings we'd done), any special features (eg. joinery, finishing), materials/components, some research and an idea about the time it'd take us. no palm cards, no real structure, like two minutes and i made mine up on the spot and covered most of the stuff we needed to speak about. i dunno what your speech is about but you should've done and be able to cover everything you need to, considering the stage in the year we're at. i can't imagine it to be lack complicated.