I just bought myself a sewing machine and finally had a go at making "hippie jeans". I followed the tutorial here: http://thenewnew.blogspot.com/2009/04/how-to-refit-old-jeans-with-side-panels.html
But I made some modifications.
First, the jeans I reconned were about 3 sizes too small, so my patches were quite wide. The height of the patches was cut randomly, but usually between 2" and 4" per patch. [See Fig 1]
Second, I have very curvy hips, so I had to reduce the patches by 4 inches to fit my waist (4 inches per side - total of 8 inches). So, I used a french curve to curve the top patch out to accommodate the hip/waist difference. [See Fig 2]
Third, I messed up and made my patchwork panels too short, but didn't figure this out until I had sewed them onto the jeans. So, I had to improvise a way to finish the hems. This is what I came up with. [Fig 3]
This was a lot of hard work, but now I have my very own patchwork jeans
Also, I am not the world's greatest sewer, so this gave me a chance to learn the features of my machine and attempt to sew in straight lines.
Some more details: The inside is lined with an old sheet. [Fig 4]
I serged the main seams, but pieced the patches on my regular sewing machine.
If I did this over again, I would make the waistband elastic MUCH tighter. I followed the tute (i.e. elastic length is one inch less than actual measurement), but the elastic is still not tight enough and I have to belt these pants. But, they are very comfy.
Here is me modeling the finished project [Fig 5]: