I'm an inveterate tinkerer with my gear, always trying to "improve" it to my liking. I assume most posters on the MYOG forum are as well.
My latest project is upgrading a new, large CamelBak daypack. It's the 2,500 cu. in. "Commander (Cabela's.com). Unfortunately for a pack this large it has no frame and only an unpadded cloth waistbelt.
1. I bought 2 strips of 1" aluminum bars (1/8" thick) and will melt holes in the pack's back for stainless bolts and fasten the pre-bent stay bars to the pack W/ s.s. washers and Nylock nuts. Did it once before on a big daypack and it worked well.
2. I've ordered an REI Ridgeline padded waistbelt and I'll seam rip the side stitching on the pack's lumbar pad, bar tack the seam ends and slide the REI belt behind the lumbar support, just like REI does on the Ridgeline pack.
3. I'm adding external bottom 3/4" webbing straps and quick-release buckles to hold a closed cell RidgeRest mat.
4. I can use the OEM side compression straps and pass them through the attatchment webbing on the back of my REI add-on side pockets for another 500 cu. in.of easy access space. The bottom compression straps have ladder buckles I'm replacing with quick-release buckles for faster threading through the side pocket's webbing. Details like this make for easier use in the cold for less "fumble time" with cold fingers.
All this is to have an easy to carry pack for day-long backcountry skiing and be able to have a comfortable emergency bivouac with my W.M Megalite 32 F. bag, Ridgerest pad and a small tarp and extra food and ESBIt tabs and "stove" W/ 1/2 L. pot. Of course I'll be carrying an avy shovel, probes, and all the other necessary avy gear. Included will be mittens and an insulating layer of Thermolite jacket and pants for severe weather and/or sleeping.
The max weight may be around 30 lbs. but with the aluminum stays and REI padded belt it will ride comfortably and stay balanced.
"There are no comfortable backpacks. Some are just less uncomfortable than others."