Half Pieced Triangles
If you want to make half square pieced triangles, I would cut 5" squares, draw a diagonal line from one corner to the other. Stitch quarter inch seam on each side of the line. You will end up with squares approximately 4.625"(4 5/8). Trim to 4.5" and that would give you a 4" finished pieced triangle with NO waste. Layer cakes are a bit on the expensive side so the old saying "waste Not want Not". Good luck !!