I got some nice comments on my latest pair of trousers (both here, and on Wardrobe Refashion) and with them, some questions about the pattern. The pattern is, like that of most of my creations, drafted by me. Therefore I can't give you an easy route to making them. However, I can share a few simple tips.
If you're going to alter a pattern, any pattern, use one you've used before, or make a muslin first. Use that to sort out the fit.
For this project, you need a fairly basic trouser pattern. Leg shape doesn't really matter but the pattern should be fitted at hips and waist and, if you want a style like mine, have a fly front, a waistband in curved pieces and scoop pockets.
To make things easy for yourself, trace the main pattern pieces (front and back legs) on a new piece of paper. Then, you alter the leg shape like the (very clumsy) drawing shows. Starting to widen the leg at different points will result in very different looks. Start at the knee and you will get a boot-cut to 70's flare, depending on the width at the bottom (see the jeans in weekly outfit nr.9). Start at the hipline/crotch and your trousers start looking a bit like culottes. For my trousers, I started widening the legs at about mid-thigh, flaring out more from the knee down. At the bottom, they are between 55 and 60 cm wide. Of course, I don't have to tell you that to get a great end result, the bottom width should be considered in relation to the rest of the measurements.