I use tracing paper to trace the parts. Then use spray glue and attach them to a 1/4" ply. Cut them out with a scroll saw and sand smooth (pic 1). I set up a trim router with a stright cutting bit with a bearing on top (pic 2). 4 stright pins hold the balsa while cutting parts. Use high speed on the router to pervent tearout. As you can see (pic 3) I cut all the wing ribs in about an hour and everyone is absolutely the same. This set up works great for me. I'm building a Das Ugly Stik from plans. All the wing ribs were the same size but with different cutouts for spars. Cut the ones with the same cutouts first then opened whatever cutouts I needed for the next group. Hope this helps.