It still surprises me that the main color in Twilight's mane and tail is more blue than purple. I have to think of it as "indigo" to get it right.
Prismacolor pencils on Strathmore sketch paper
Edit: Please see this lovely vectored version by ! She did a great job.
There's already a vector version out, but I'm hardly going to spoil your fun.
THIS IS FREAKING AWESOMESAUCE!!!
Does your sketchbook not have perforated pages? Mine does, so I can tear the sheets out neatly. Sketchbook paper takes color better than printer paper, and printer paper is way cheaper, so I use the printer paper for sketches, and color the final piece on sketchbook paper. You could always cut sheets out of your sketchbook with scissors, but that's up to you.
Even with those flaws it still comes out pretty good after I crop it in Paint and fix it up a bit in Photoshop. I'm just a bit hesitant about cutting the pages because I have no clue where I would put them after I'm done with the drawing. lol.
And the custom light box, that sounds pretty easy to make. I've got some of those things in my house actually. I might have to do some scrounging around for some glass to put inside the picture frame, but it could be worth it.
I've been thinking of getting a hanging file to keep my loose art in. Cardboard ones are pretty cheap, and there are some that are just wire frames, or that stack neatly in crates. That would let me organize them, too.
The picture frame already had glass in it.
(Though, uh, I made a mistake in my drawing that seems to have translated: Her cutie mark is missing the little stars, and the white detail on the big star.)