Pick the shape first: a boxy tee, a cropped hoodie, a wide cargo pant. Starting from a template or from a garment you already like saves a lot of guessing. Change one or two things at a time, not everything at once.

Flat sketches are drawn as if the garment is lying on a table, not on a body. Always include the back. Many details are only on the back, and factories can't guess them. Add short callouts, like "2.5 cm twin-needle hem".

Choose a sample size (usually M) and measure the garment laid flat. For each point of measure, write the M number, how much it grows or shrinks per size, and the tolerance. Example from our free tee: chest width is 60 cm at M, changes by 3 cm per size (57 cm at S, 63 cm at L), with ±1 cm tolerance.

GSM means grams per square metre: a higher number means heavier, thicker fabric. Everyday tees are often around 150–200 GSM. Boxy streetwear tees are usually heavier; our free tee uses 260 GSM cotton jersey. Hoodies are heavier again, often 300–400+ GSM fleece. Our GSM guide explains it in more detail.

Say exactly how it's sewn. Don't write "standard construction", because standard is different in every factory. Example: "5 cm drop shoulder, 1x1 rib neck 2.5 cm high, twin-needle hems 2.5 cm, 4-thread overlock side seams, 12 stitches per inch."

Write down each extra part: neck tape, main label, care label, zips, drawcords, buttons. Say where each one goes, for example "care label at left side seam". If you leave this out, the factory will choose for you.

Give each colour a name and a code (a hex code like #2B2B2B, or a Pantone number if your factory uses them). If there's a print, give its size and position, measured from a fixed point like the high point of the shoulder.

Email the PDF to a few factories and ask for a price and a sample. When the sample arrives, measure it flat against your size chart and write what needs to change. Update the tech pack and raise the version number, so everyone works from the same file.