Measure your vintage suitcase for length, width and depth. Determine whether you want to leave the leather or exterior material exposed for vintage character or whether you want to add padding and material for a comfortable seat.
Cover the seat using your upholstery tools and fabric. Use a handheld sewing machine or staple gun to staple the material to the bottom of the suitcase. Keep it even and avoid baggy or bunchy areas.
Use a hammer and nails to add the legs to the suitcase. Add a back to the suitcase. You can use wood, metal or a piece of fabric-covered board. Cover the board in fabric if you opt for this style, using the same upholstery methods as you used with the suitcase, and attach it to the suitcase with a sewing project staple gun. If you opt to use wood or metal, attach these items with screws or nails.