building a spring launcher using tension springs

im taking grade 12 physics right now and my final project is to create a spring launcher using tension springs (the ones that stretch, not squish). i have ZERO clue how to do this and im not good at this class, i have a 71 and it’s worth 20% of my grade. help!! i need ideas and i cant find anything online thats helpful (because all spring launchers ive seen are all using compression springs). its due in about a week, and i dont have a lot of money to spare for the project. please, anything helps.