Pose the weighted mesh + skeleton to match the pose of the replaced model's idle/reference sequence.

Rig/weight the custom mesh to the skeleton.

Note that sometimes some bones need rotating about the axis along the length of the bone because different games expect different orientation of the axes.

Adjust the skeleton to fit the custom mesh.

The model or mesh being replaced is the 'reference'.

Import the skeleton of the model being replaced.

Proportion trick script for GMod player model (Blender 2.8/2.9) (Video).

Proportion trick script for GMod player model (Blender 2.79) (Video).

Adjusting Proportions on Playermodels (Guide by CaptainBigButt.).

Custom Playermodels (Proportiontrick & Face Flex) (Guide by Funreal.).

Quick proportion Idle Pose Method (Video by Splinks.).

Convert GMod ragdoll to player model & NPC + proportion trick (Video by Name.).

(Forum topic where there are a few posts by Lukis that are full tutorial posts.) I'm trying to make a small playermodel, but its body is stretched-out to fit the human-body-form.Applying the Size Proportion Trick - L4D2 (YouTube video by MSF.).

How to use the Size Proportion Trick (By MSF.).QC files (Forum topic by CaptainBigButt with explanations and link to example files that use the Proportion Trick.).

Information that the tutorial is based on

For example, by using the trick, a modder can replace L4D2 Zoey survivor model with a custom woman model that has longer legs and is shorter from head to torso than Zoey and still uses Zoey's existing animations without having to change any of Zoey's animations. The trick forces the animations to conform to the custom model's skeleton rather than the other way around. Use an existing set of animations built for a different-shaped skeleton (such as for a smaller or taller human than what will be using the animations) without having to change the existing animations.

Gmod player model how to change