Shelley wrote, "When I read about how to sew clothing, all the books talk about making a muslin, usually starting with a dressmaking pattern. The problem is (well, the first, there are probably many) that my books tend to be rather vintage and the commercial patterns they suggest seem to be out of print. Is there a commercial dressmaking pattern you could recommend for a novice sewer for this purpose? I’ve dreamed of making my own clothes for most of my life and it’s time to either get on with it or give up the dream. I’ll be very grateful for any advice you might give."
It's sounds like you are referring to a "sloper" or "block" or "fitting shell" rather than a muslin. Back in the day, all dressmaking books suggest making a sloper and many modern seamstresses still swear by them. The basic concept of a sloper is that you create a snug fitting dress (usually, but you can create a pants sloper as well) that has a bodice, with sleeves and straight skirt joined at the waist. For example, below are the dress (V1004) and pants (V1003) fitting shell patterns offered by Vogue. This Burda Style link also provides other sloper resources.
The goal with the sloper is to create a garment that fits you like a comfortable glove. Using your personal measurements, you want to make changes to the sloper to ensure that all your unique fitting issues are addressed. For instance, I would adjust for my small shoulders, yet relatively broad back, as well as my small waist, tiny bust and large hips. For work clothing, I would ensure that my bodice and sleeves allowed me to write comfortably on a chalk board (I'm a teacher) and that my skirt would have enough sitting ease.
Once you have a well-fitting sloper, then you can use it to check the fit of commercial patterns you may wish to make. This is done by laying your personal sloper pattern pieces over the commercial pattern pieces to look for any changes to be made. For instance, I would check that the shoulder length and armscyce are the correct dimensions and adjust accordingly. Or you can use the sloper to draft patterns of your own. This is done by adding design elements to your basic sloper. For example, you could slash your sloper to add interesting seaming details or colour blocking effects. Check out this sloper series, as well as the link above, for more details.
All that said, I do not use a sloper. I have been sewing long enough that I can just flat pattern measure vital areas (shoulders, bust, waist, hips, etc.) and add or remove tissue to accommodate my particular measurements. If I am planning on using a very expensive fabric or if the pattern is very intricate, I will create a "muslin" or "toile." A muslin is a quick and dirty mock up of the desired garment in a fabric of similar weight and drape to the final fashion fabric. All major pattern pieces are used (bodice, sleeves, collars, skirts, etc.), as well as any closures (zipper, buttons, etc.), but facings are not. This allows me to determine if the major fitting issues are addressed before cutting into the good fabric. Often, if the garment is to be done in a forgiving knit/stretch woven, I will throw caution to the wind and just go for it, after a few quick flat pattern measurements.
I am also a fan of using TNT ("tried and true" or "tested and true", depending on who you ask) patterns. These are patterns that I have made over and over, tweaking the fit on each successive garment until I have the perfectly fitted pattern. I have several TNTs - pants, tops, skirts, dresses, jackets and coats - and by simply using an array of fabrics, I can get many different looks. As well, I will add or delete design details to arrive at a completely different look.
So, I guess the moral of the story is that you have to decide which method suits you the best - sloper or muslin or just diving straight in.
HZC readers, how 'bout it - do you have any additional info or insights for Shelley?