13: you are underestimating yourself. If you are strong you might very well be able to build props (using cardboard, corrugated plastic etc.). It probably doesn’t need to be made from wood for one time use; then paint and the audience won’t be the wiser. Props are fun because they won’t be inspected by the audience from up close.
There are diy tutorials online for almost anything. Ask an adult to search and print for you if you have limited access. You don’t need to find the exact thing to get inspiration. Then get girls to brainstorm with you if get stumped. Have someone do the drawing if you can’t. Get your family involved in the logistics of the building process. Branch out a little from your comfort zone. Being strong is good, capitalize on it — cutting needs muscle too!
I’m not trying to be preachy but I’m talking as a “late bloomer” who used to think she has zero creativity.
Your school will thank you for the savings but you’ll benefit the most. Have fun and good luck!