Extending the waist band of cargo pants

I have a pair of cargo pants that didn't fit me anymore. The legs were fine, but hips and waist required extension. I've never done anything like this, but decided to try anyway as the pants were of no use to me as they were. So I opened the side seams down to the upper edges of the pockets that are on the sides just a little over the knees.

Then I cut wedge shaped pieces out of black 100% cotton. I bought the fabric specifically for this purpose. For some reason, the instructions that came with the fabric said it should be washed in 40 degrees (C). 100% cotton should be able to take 60 (the pants certainly can), so I washed the fabric first to make sure of that.

I pinned the wedges in place and tried the pants on to make sure everything was fine. I made the waist slightly too loose to take into account possible future weight gain. There are straps on the sides to make the waist tighter, so I'm using them now to get the waist to the correct size.

At this point my sewing machine stopped working, so I had to take it to be serviced, which took 10 days. I had to stop all of my current projects for that time as they all require the sewing machine. 

Sewing the seams was one of the most difficult projects I've done so far, but at least the sewing machine was freshly serviced and wasn't causing any trouble.

After sewing the wedges in place, I had to fix the inside of the waist band. When I opened the side seams, I had to cut the band that was going around the inside at the waist, and now it required extensions as well.

Here is an extension sewn in place. I have no idea how these things are supposed to be made, so I've just done everything in this project as I have seen fit. There are probably some unnecessary seams in places, but black thread on black fabric isn't too noticeable, so it doesn't matter.

As I had already seen so much trouble with these, I decided to also shorten the legs, which had always been a bit too long. It hadn't bothered me as I mostly used these in the forest and put the pants legs inside the rubber boots. Now I'll be using these during the winter in the city, so it's nicer to have them at proper length.

In the picture above, I'm wearing the pants with the side straps set as shown in the following picture. I can get the waist just the right size, but also adjust it in case of temporary bloating or some more permanent weight gain.

The final thing was sewing a button in place as there was one button missing. This kind of pants are great because there's no zipper to be replaced, but on the other hand, buttons have a tendency to fall more often than a zipper breaks.