I've been experimenting with Judy Barlup's style of making welts and flap pockets and really like the bulk-free result of her method. I found a step-by-step tutorial on this web site. This gives you the dimensions of the pocket pieces, all based on the size of your finished welt. I first copied the welt pattern from this site and manipulated the size on the computer until I had what I thought I wanted, but I found that the pattern had gotten slightly distorted and the seam allowances were uneven. So instead, I created a tutorial (link above) for creating a Judy Barlup-style welt from scratch, starting with the dimensions you want your finished welt to be and building from there. This is for the horizontal or vertical welt and not for the angled welt that she also shows on the web site. I haven't experimented with that one yet. You can use these directions to make any size bulk-free flap or welt you want. I hope it's clear!