I'll certainly try and enter this time around. I have a decent idea I think, just need to pull it off.
As for interpretations, I think there's more than just an actual prism. Prismatic can really just mean "many bright colors".
Light reflecting off a shiny object
A field of colored flowers
Someone tripping on LSD!
A brightly colored nebula
A pile of diamonds
What? I bet you can draw better than what you think...
best not to think about drawing and just draw! But don't draw without thinking. Always draw with the intent of learning and experimenting but don't let it all weigh you down at once. Even the greatest started with a squiggle.
And some artists when using digital media sketch on a pad of paper and take photos/scan and paint on top of it... (just dropping possible aid whereever I can...)