Generally speaking, the most recommended way to go about sourcing customized tapered or angled nets is to have them produced with a 5/16" Dacron® rope bordering sewn-in around the edges. This will greatly help the mesh hold its shape, and significantly increases the amount of strength around the perimeter (which is usually being clipped/hooked-to for the hanging and usage of the netting).
And from Gourock.com, we supply angled and custom nets built from the DuPont® Type 66-728 Twisted-Knotted Nylon Netting. There are a variety of mesh sizes available, and you can consider 3/4", 1", 1-3/4", and 4" (your purpose/application for the netting will determine which one will be a best match). And then there are different twine thicknesses available as well, ranging from a #12 (1.7mm) to a #72 (3.5mm). For some additional context on these options you can visit this page of the Gourock site (click).
Here are a series of production diagrams that show some of the angled and tapered custom netting panels that Gourock has had fabricated and shipped out over the last few weeks. These nets were built for private homeowners for multipurpose barrier needs, commercial sports facilities for indoor barrier installations, customers with a necessity to protect their property from golf balls, solar panel protection, and residential sports containment and impact. Feel free to contact Gourock for a quote if you have similar netting needs and we can take a look at your request for you, no problem at all!