A prototype, by necessity, is often created with materials that are different from the final product. Not only will you not be able to source some types of product before you move into production, but you'll also need to create a proof of concept before trying to lower costs and streamline. With that in mind, here are some of the major considerations to make when choosing fabric.
Find a Fabric That is Easily Sourced
You want to do some preliminary research into your materials to make sure that the materials you're using can be sourced through multiple distributors. If it is a rare type of fabric, you may have trouble getting it down to a reasonable cost, or you may find yourself without it if your distributor runs out. The more common the fabric is, the easier production and manufacturing will be.
Identify Any Core Aspects
What are the core features that your prototype is going to have? Identify the core aspects of your brand that would need to shine through in terms of material. As an example, if your brand is contemporary and modern, you may need a sleek, shiny fabric. If your brand is a luxury brand, you will need a thick, high quality fabric. These are the major characteristics you'll need to find.
Test in the Right Environment
Before you commit to using fabric for your prototype, test it in the environment that your prototype will be used. Fabric is often the weakest point of a prototype, compared to other materials such as rubber, plastic, and steel. You need to make sure that the fabric can withstand the environment that you need to use it in. Sometimes that may require some form of treatment, such as a heat-resistant or water-resistant coating.
Look at Similar Products
Finally, you may want to look at similar products for guidance if you aren't certain which type of material to use. Products that are used in similar ways or similar environments may have different ways of approaching the same problems, in terms of flexibility, durability, and appearance. You can learn from what your competitors are doing and find ways to do it better, by looking at common complaints and issues.
You can usually get samples from fabric distributors in the form of apparel swatch cards. These swatch cards can be used to determine the thickness, weave, and durability of your material before you choose to use it.