you could do something like fake marketing your own brand. If you have a hobby like bracelet making lets say you could research if people like them or if they don't, you could also do showing the graph of the cost per hour it takes to make, then maybe when presenting you could actually sell your bracelets to prove a point? I'm a senior as well and I haven't even started my project either but this was one of my ideas
Do whatever you love to do within reason. So like, if you love to bake, then you should sell cakes, or cookies, if you love to make crafts... etc. Do what you want to do or try something out that youve never done before!