Jeans that already fit you well in the hips are important for this DIY, and stretchy denim works a lot better for the snug fit I like to achieve. I did three pairs yesterday. Some shiny black pants that I think used to belong to a 14 year old girl. 1980's high waisted stretchy mom jeans, and some high waisted flared blue jeans.
Alright, to begin
Assuming you already own one pair of skinny jeans, lay them over the top of the pants (that are turned inside out) you wish to reconstruct. Line up the inseam of the jeans as best you can with the skinnies on top, and make sure the outer seam of the jeans is laying flat. (Jeans are made so the panel of fabric on the back of your leg is wider than the front, and you need to keep it this way so they fit well.) See the photos for how the edges should look. This is the most important part of the whole operation.
Grab some chalk.
Starting about mid thigh, trace along the edge of the skinny jeans so you know where to sew. Curve in a little bit for the knee, curve out a little bit for the calf, make them straight down, whatever you want! You're in control. A lot of people put them on inside out and pin them along their legs, but after doing that and poking myself a bunch and having the pins fall out, I just use my favorite worn in jeans as a guide. Again, stretchy denim helps get you a good fit.
Start on the seam that is already there, backstitch a few times, and carefully follow your line all the way down making sure the edge of the denim remains flat. (Pins work for that.)
Ta-da! Skinny jeans. See them in action here
As always e-mail me with any questions. lovecharlesvintage (at) gmail.com