I havn't made any as my kids are way past that time in their life,but i do know there are patterns for them in all the pattern books.I think how they hold up would depend on what they are made out of.I personally think denim would hold up well,may be a bit heavier though than the nylon so many of them are made from.JMO
kathi

I used to buy my kids the more expensive backpacks from Eddie Bauer and ones by Eastpack. They all ways lasted for many years AND they have a lifetime guarantee! I think we had to mail them back for repair or replacement only twice. Once for a new zipper and once for a hole in the bottom. They stood by the guarantee!
Trust me, my boys were tough on them.
Kathy G in MI

A couple years ago of the BP that came apart at a seam...I ripped apart(seam ripper) and used that as a pattern...salvaged the straps,put new zipper in, added seam allowance...used denim (no liner insert)...I kept it basic meaning no extra pockets, zips so on...They used for a couple years, now I store extra clothes for GS when he comes to visit and it's still intact...

IMO, it wasn't hard, but as i'm always pressed for time I kept it simple...I did have a few old backpacks to choose from and picked the simplest...I got tired of those bought ones coming apart or breaking...and it was mostly done to refresh sewing skills...I use to be an avid sewer...but now it's whenever I get the urge...

juanital

Simplicity, Mccalls and Butterrick all have patterns. I have made them and they are not that hard. I had a friend that was very new to sewing and made them without any trouble.

Lynne

I made my dotter a backpack more than 15 yrs ago. I used an old backpack that I cut apart for the pattern. Used a light colored demin. Dotter needed a small lightwieght backpack that would breathe as she had to keep meds with her at all times so I wanted something light that was light colored an breathed so it would not be hot on her back either.

The backpack is not used as much as it once was but is still in use. Still looks new too. It has been used for many many things over the years as well and has been washed and washed which has been a very nice feature to beable to just throw it in washer and dryer.