Name for expert sizing by a tailor

Solution 1:

Rock of Eye

Example sentence including a definition:

For interim fittings, "Rock Of Eye" (which means trained freehand based on an experienced artistic eye to match the item to the wearer, trusting the eye over unyielding scripted approach), drawing and cutting inaccuracies are overcome by the fitting.

[Wikipedia]

I could not find a Jewish term for that.

I found rock of eye by searching "a tailor who can fit by eye" (which returned about 83,500,000 results). The first sentence from the first result returned follows:

If one enters the world of tailoring (in any era), it is usually not long before you hear of some mythical era of tailoring when tailors could do everything with regards to drafting and fitting with their ‘rock of eye’. — James Williams (historical taylor)

From "Developing the Tailor’s ‘Rock of Eye’" (2 OCTOBER 2018). [historical-tailoring.com]