In every render we have resources for bind item or avatar for svg, its ai or psd files, which have parts and mask for render.
We have helpers/dna-parser.js file, where we have logic for getting json objects with params for every renderer, for avatar and items its object are differnt
In this file controllers/api/nft.js we getting params for image, its width, height, type, and id image and depend of type, we geting HBS file in folder 'layouts' and binding render