Hi new to forum and new to woodworking so go easy on me. I come to woodworking as an art teacher who, along with my students, has created a bunch of functional cardboard chairs. I’d like to try to make a few out of actual wood. The designs have acute angles involved in them. I’d like to use some type of joinery and glue to build them entirely. My thought is to run a tenon all the way across the 18” boards at an angle and then slip those right into a mortise that also runs across the board at an angle. I have a table saw and tenoning jig to work with but I don’t think it’s possible without some other type of jig. To be clear I’ll just use a part. Picture the top of an acute triangle that has 18” depth looking from the side of the chair. I want the back angled board to butt up flush to what will be the back rest angled board connected with a mortise and tenon that runs all the way across. Any ideas on how to cut it?
edit I attached a picture. I want it like that but longer and at an acute angle. It’s under 45 that’s an issue.