craftgrrl | I was up all night ironing pleats!

I've never made clothing before, so this is all very new to me. I just had a crazy idea about pleats and the flats and sharps on a keyboard (didn't show up very well in the photos), and I couldn't rest until I'd tried it out. I didn't have a pattern to work from, so I ran out of fabric for the pleats at the back. Whoops!

I don't have a sewing machine, so I had to hand sew most of it until I could borrow one to do the hem. All-in-all it's not quite what I envisioned, but I kinda like it. :)
Anyway, I was just wondering, for now and for future reference, is there anything simple I can do to make the pleats stiffer, or more permanent?