Start with the frame
A cushion should suit the usable seating area, not just resemble the old cushion. Share a straight-on photo, the frame dimensions and any details such as curved backs, arms or separate seat and back pieces.
Choose the feel and finish
Thickness, firmness, piping, ties and fabric direction all affect the finished piece. Discuss those choices together so the cushion looks proportionate and supports the way the furniture is used.
From dimensions to a repeatable pattern
Digital patterning and CNC cutting help carry approved dimensions into the fabric pieces. A written specification should confirm the final sizes, quantities, material selection and construction before production.