How about starting a school library, if there isn’t one already. Parents/Grandparents/ etc… can donate books l’zecher nishamas or as a z’chus for someone. Ongoing income and the school gains the books and the donation!
Also, how about taking individual pictures and/or class pictures and sell packages to parents/grandparents. With digital pictures and printing is so simple and it’s pretty hard not to take a nice picture. And who wouldn’t buy a picture of their own kid?