Putting on the pants.

Foam was added to his legs to fill out the pant legs,

Then cloth was glued and pinned onto the foam, also foam added behind the legs and belly, as wizards are frequently well fed.

The last picture shows foam on his back placed where the fabric would have folds. Most of that was removed before the fabric was placed.

Collar at the neck was made of foam and covered with cloth. It was removed in favor of a cloth collar.