Search for “vintage/retro school chairs” on Ebay and Etsy or buy one from Cult Furniture or Smallable.
You can either make your own letter stencils or buy them here
1. Place letter stencils on the back of the chair and hold in place with masking tape (Cover the rest of the chair in newspaper to avoid it getting covered in spray paint)
2. Spray paint onto stencil in short even applications, once the paint is dry remove stencil and newspaper
3. If you are feeling creative and dont have the stencils then try spray painting the chair legs your kid’s favourite colour