Your interior modules are fiberglass. But they can be painted. After proper surface preparation (thorough cleaning, light
sanding, thorough cleaning) I had good luck using Rustoleum "Appliance" spray paint
If your modules have surface imperfections, these can be filled/repaired with a variety of options (including: fiberglass resin with a colloidal silica adhesive filler; "Marine-tex"; and/or Interlux surfacing putty) before you paint.