Thanks for the kind words. Actually, I've made half a dozen over the years, but not for quite a while. Mostly I've used the same basic design, but with somewhat heavier materials. There's a link in the MYOG post with the title, "need suggestions for pack" if you want to see one.

For the zippers (both for lid pocket and on front panel) I used #5 YKK continuous zipper. I just sewed across the ends rather than using zipper stops.

I made the big pocket on the front by starting with the main front panel extra long (maybe 18" or so). I folded it toward the inside of the pack, then back up, making a pocket about 8" deep. Then made another fold above the pocket opening, this time outward-and-back to form the zipper flap, then the material continues on up to the drawstring. So it's all one piece, with one side of the zipper sewn to the first fold, and the other side sewn behind the zipper flap, making sure not to sew it too close, or the flap will constrict the zipper.

Then when the front panel is sewn to the sides, the zipper ends are sewn over at the same time (making sure to put the zipper pull on first.)

I hope that gives you the general idea. As far as zipper installation itself, I imagine there are a ton of YouTube videos on the subject. There's useful tips on thru-hiker.com and also therainshed.com. #5 is about the right size for pack pockets, sleeping bags, and the like. #3 is very light, and works for ultralight clothing and netting zippers on ultralight tents. #8 is for heavy duty stuff, like duffelbags, and #10 is heavier yet. Be aware that there have also been #4.5 and #7 and maybe others. It's a good idea to get the pulls from the same source at the same time as you get the zipper. Also, there are locking and non-locking pulls. The locking ones require a "downward" pull to unzip. Best to avoid for backpacks.
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Always remember that you are absolutely unique, just like everybody else. -Margaret Mead