A tech pack is the instruction manual for your garment. It's what turns a design on paper (or screen) into something a pattern maker, sample room, or manufacturer can actually produce without guessing what you meant. A strong tech pack is the single biggest factor in whether your first sample comes back close to what you imagined, or whether you spend three rounds of revisions fixing avoidable misunderstandings.
What a tech pack needs to include
Header information. Style name, style number, season, designer name, date, and size range. This sounds trivial until you're managing twelve styles at once and can't tell which version of which file is current.
A flat sketch or technical drawing. Front and back, to scale, with no styling or shading — just the construction lines a pattern maker needs: seams, topstitching, closures, pockets, hems.
A bill of materials (BOM). Every fabric, trim, and notion that goes into the garment: fabric composition and weight, lining, interfacing, zippers, buttons, thread color, labels. Include supplier and article numbers if you have them — guessing "a zipper" instead of "YKK #5 coil, 7 inches, antique brass" is how the wrong zipper shows up in your sample.
A measurement spec (spec sheet). Point-of-measure by point-of-measure — chest, waist, hip, shoulder, sleeve length, and so on — with a tolerance for each, at your base size at minimum, ideally graded across your full size range. This is the single most common source of "the sample doesn't fit like the sketch" problems.
Construction and finishing notes. Seam type (e.g. flat-felled vs. serged), stitch length, hem finish, anything unusual about how a piece should be assembled that isn't obvious from the flat sketch alone.
Colorways. If the style comes in more than one colorway, show each one with its own color codes — Pantone or a supplier's own reference, not just "navy."
Common mistakes
Sending a tech pack with a beautiful rendered sketch but no flat construction drawing. A sample room works from construction lines, not a lookbook image.
Leaving measurements as a single number with no tolerance. "Chest: 38 inches" without a tolerance invites a sample that's technically correct and still wrong.
Treating the tech pack as a one-time document. A tech pack should be versioned — track what changed between v1 and v2 so a sample room (and you) can see exactly what was adjusted and why.
Building one in GDH Studio
GDH Studio's Tech Pack Tool generates a tech pack directly from a garment version you've already built: it pulls your header info, bill of materials, measurement spec by size, construction notes, and approved renders into a single exportable PDF — so the tech pack stays in sync with the actual garment data instead of being a separate document you have to update by hand.
