Lazy crayon roll tutorial

I made this crayon roll in the hopes of giving a little cheer to my friend's son, who has just started up with chemo again. I'm hoping that he still likes dinosaurs...
I have seen lots of crayon and pencil rolls on blogs and always thought that one would make a nice wee gift for a young child. . .nb. for some reason I tend to search for tutorials after I have made something, to see if I have made it correctly, rather than before, which would make far more sense... I did decide to make it a little different from the ones that I have seen so far, though. If you take a look at this photo, you'll notice that you can't see the stitched lines separating the crayon pockets. I do like the look of the stitched lines, but this way I can make it a little quicker, as I don't have to be so careful about making the stitched lines even and neat. Hence, this isn't a new idea, by any means, but this is the lazy version of the crayon roll.
I made this one for the triangular crayons, which are a little larger than normal crayons. I sandwiched one between two scraps of material and decided that 1" wide pockets would be a good fit. Normal crayons would probably need just ¾" wide pockets. I'll use the measurements for 16 larger crayons in the tutorial, but at the end you will find the approximate measurements for a crayon roll of 24 crayons (see italics).
For 16 large triangular crayons:
1. Cut out
...........1 18½" by 5½" rectangle of the exterior fabric
...........1 18½" by 5½" rectangle of interfacing or flannel
...........1 18½" by 12½" rectangle of the interior fabric

2. Measure 5½" down from the top of interior fabric rectangle and draw a horizontal line (A to B). Fold the fabric along this line so that the right sides are facing. The slightly larger side should be on top.
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3. Mark a horizontal line (C to D) 3½" up from the fold (A to B), then mark parallel vertical lines from this line to the fold every inch along the rectangle (shown by red dotted lines). Sew along these lines.
4. Fold the front half of the fabric down along line C to D, covering the lines that you have just sewn.
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5. (Iron on the interfacing to the wrong side of a fabric rectangle if you are using interfacing. If using flannel place the exterior and interior fabrics right sides facing on top of the flannel) Line up the interior and exterior rectangles right sides facing, pinning a small elastic hairband to one of the short sides. Sew around the edges using a ¼" seam allowance (as shown by the red dotted lines), leaving a gap on the final short side for turning. Make sure that you catch the edge of the elastic loop when you sew that end.
6. Turn it right sides out, press, then top stitch around the edge. This will close the opening.
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7. Put the crayons in their pockets, roll it up, then sew on a button at the point that the elastic loop reaches. Done.

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For 24 regular crayons:
The smaller rectangle will be about 20½" by 5" (24 crayons multiplied by ¾" pocket width, plus an additional inch for either end plus ½" seam allowance)
The larger rectangle will be approximately 20½" by 11½" . Measure 5" down to make line A to B, then measure 3 ¼" up from that fold to mark line C to D. To mark the parallel pocket lines, start one inch from the left edge, then mark every ¾" across, until you have 1" left.
You can use a ribbon to tie it, instead of a button and loop - just catch the ends of the ribbons as you sew the edge.
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Tell me if you have any questions or if you notice any glaring errors. The friend that I attempted to teach algebra to can attest to the fact that I am not any good at explaining things. I'd have taken pictures as I made it, but I thought, 'oh, that's an easy thing to explain', apparently forgetting that it would be me attempting to explain it...
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Translation of the day:
UK English: revise = study (usually before an exam) in US English
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As in, I think I might be dragging out my old maths books and doing some revising soon, if my 5 year old son is already bringing home geometry homework...