Basic pattern altering is very simple, no need to draft your own starter block, or work through one of the big pattern making textbooks.

List of simple methods of altering a pattern is in this post from Sewingplums.

Instructions for specific changes :
See this page of Sewingplums – Pattern altering to make new styles (click link to go to section on ‘altering patterns’).

Dozens of simplified patterns at Sew Guide.

If you prefer someone to do the pattern work for you
This post from Sewingplums has links to many patterns with extensive variations (patterns available mid-2017).

Some of the sources available since that was written :
Atelier Charlotte Auzou, choose patterns for bodice, sleeves, skirt.
Named Clothing patterns Anni building blocks, for a princess seamed bodice with a variety of sleeves and skirts/pants.
Simplicity patterns ‘Hacking’ patterns.

Start with a few basic patterns and make style variations

No need to draft your own personal blocks to do this.
Though if you would like to try that, Cal Patch’s Design It Yourself Clothes book has simplified block drafting instructions, plus instructions for many variations. Written pattern making instructions with few illustrations, minimal sewing instructions. I prefer her video classes at Creative Bug.

Base patterns supplied ready made :

Pattern companies which supply base patterns with personal fitting instructions, plus many variations :
Many of the variation instructions could be applied to other patterns with a little thought.

Alison Glass Essentials (scroll well down), basic patterns for woven fabric and knit fabric dresses (body bust 31″-50″). Pattern includes instructions for fitting and style changes.
Fit For Art, basic patterns for jacket, pants, knit top (body bust 30″-58″). Separate patterns for variations.
Fit Nice , basic patterns for top, pants (body bust 32″-42″, instructions for larger). Separate patterns for variations.
Sure Fit Designs, basic patterns for dress, shirt, pants (body bust 28″-62″). Pattern booklets include many variations, more can be bought separately. There are also pattern change videos at SewFit Academy.

Books which include starting-point patterns and instructions for many variations :
(skirts and pants all have elastic waist)

in print : The Act of Sewing by Sonya Philip, basic patterns for cut-on sleeve top, sleeved top, skirt, pants (sizes XS-5X). Instructions for DIY changes to patterns. Similar pdf patterns with variations and sewing instructions in her video classes at Creative Bug.

out of print (many ideas but rather dated pattern proportions) :
Easy Sewing the Kwik Sew Way by Kerstin Martensson (2002), full size traceable patterns for basic blouse, knit tee, 2 skirts, pants (body bust 31″-45″). Includes patterns for variations.
Making a complete wardrobe from 4 basic patterns by Rusty Bensusssen (1987), grid diagrams for basic patterns for top, 2 skirts, pants (garment bust 54″-56″, easy to change by using fewer or more grid squares). Instructions for DIY changes to patterns.

Many routes to starting on making your own styles, if the thought of that appeals ! Enjoy 😀

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