One of the less glamorous aspects of making clothes is making patterns -- the process of taking an idea and drafting a set of pattern pieces that, when sewn in fabric, will reflect the original idea and fit the curves of a body. Paper is one of the most important tools, so there are different types for every stage of the pattern-making process.
When I work on patterns, I tend to use three types of paper: medical paper, alpha-numeric dotted paper and manila tag board.
Medical paper -- a thin, slightly transparent paper that is often used in medical offices -- is ideal for design testing. It is delicate and tears easily, but it is the least expensive option, so it is easy to make mistakes and toss them into the recycling bin without feeling guilty! Medical paper is also great for tracing commercial patterns, so you can keep the original patterns uncut and pristine, in case you need to make different sizes in the future.
For patterns with folded details, such as pleats, medical paper would work well for the pleated inserts. In the pattern piece above, the folded pleats were kind of stiff to work with -- medical paper would have made it easier and neater to fold.
After the patterns have been refined, they can be traced to alpha-numeric dotted paper, which is thicker and has "dots" of letters and numbers that can be used as guides for grainlines, CF and CB lines, etc. The weight of this paper is similar to standard printing paper, so the patterns made from this paper are much sturdier than those made with medical paper. It is more expensive, so it is ideal for near-final patterns as well as for the final set of pattern pieces for a design.
Manila tag board is a stiff paper that is perfect for pattern pieces that will be used often, such as slopers (base patterns for a given size). In this photo, the tag board sloper is beneath the pattern pieces that were drafted from the sloper.
Manila tag board is an indispensable paper for slopers (base patterns) and designs that are made multiple times. Because tag board is as stiff as card stock, it is sturdy and can be used many times. It comes in different weights, but the heavyweight variety (150 weight) seems to be the most versatile. It is more expensive than the lighter weight varieties (100 or 125), but it is worth it, because patterns transferred to tag are meant for heavy use and longevity.
Here are some resources if you are interested!
Medical Paper: Medline Exam Table Paper (Amazon)
Alpha-Numeric Dotted Paper: IDS (International Design Supplies)
Manila Tag Board: Atlas Levy Sewing Machine Co.