prototype for designer garment

[annebryan]

What is the name of a prototype for a designer garment made with cheap cloth

[luwarm]

I think it's a 'muslin'. Then after the muslin is made and altered, it is then called a prototype. The prototype is then used as a sample of the final garment if no more changes need to be made.

[Naomicorlett]

Toile is the dress made in cheap fabric. I've just done one to get fit on new dress well worth it if making item in expensive fabric.

[Mr Veritas]

It depends on whether you are in USA or outside of it.
This is from Wikipedia:~

Test garment
A toile is a version of a garment made by a fashion designer or dressmaker to test a pattern. They are usually made in cheap material, as multiple toiles may be made in the process of perfecting a design. Toiles may be called "muslins" in the United States

So you are both right,but in the UK and Europe it's known as a toile.