You will need...
A pale coloured garment
Pebeo Setasilk silk fabric paint (for drizzling)
Dylon fabric paint
A thick brush (I used an old blusher brush)
In principle, it couldn't be simpler, however there are two caveats: results may vary depending on your technique; and, the not-so-easy challenge here is to keep your work surfaces clean. Prepare to get messy!
Mine took about 10 minutes.