• You can buy pre-cut hardboard at most art stores or through various art suppliers. You can have them cut to size at the hardware store or cut them yourself.
You can buy aluminum panels like AlumaComp or Dibond, either cut to size, or cut them yourself.
You can purchase Multimedia Artboard, which is incredibly lightweight, easy to cut, and archival. When you frame it, you will want a heavier backing board behind it to support it. It is probably too thin for plein air events where you have to have an official stamp showing on the back and they don’t want you covering it with a heavier support, but otherwise it is my first choice. Archival, travels beautifully, very light. It can also chip or break. It is the most fragile of my three choices.
• Hardboard only. Seal the surface. I use matte medium. I seal the sides, back and front. This keeps it from warping, and when I finally acrylic gesso it, it acts as a barrier from any contaminants in the hardboard. I use a housepainter’s brush and brush in several directions. I WANT some textural quality.
• Aluminum – you might want to research whether you need to apply a sealer or primer to give the gesso better adhesion.
• Multimedia Artboard. Seal the surface, acrylic gesso it. I doesn’t warp. It is archival. I just seal the front. I use a housepainter’s brush and brush in several directions. I WANT some textural quality.
• Use a housepaint brush to add some texture to your panel. A gel matte medium first will give you a little more texture. Apply acrylic gesso with your brush, in several directions.
• If you are an oil painter, you might consider waiting at least three days for the panels to cure before using. You can add a thin layer of alkyd white to the panel to give it an oil primer-like base, or buy some oil primer to add to this layer.