I'm currently working on a Blender add on that can generate thousands of images or 3D models. It does this by reading your .blend file and creating a unique DNA strand for every possible NFT you can generate. It then randomly selects however many you desire (10000 lets say) and exports them as a rendered image, or a 3D model.
Now you have a collection of 10000 NFT images, or 3D models.
From there you would have to use a website like NFT-Maker Pro (NFT-Maker Pro only works on Cardano) for whatever blockchain you are working with to upload those images and mint the NFT tokens as people requests them. (You could create a script that mints them all at once, but the gas fees would start to add up really quickly.)
Using a minting website with an API would be ideal, you could then mint your NFTs whenever someone actually wants to buy them. There are a lot more complications that you would run into, but that would be the rundown of the fundamentals.
For more information about the Blend_My_NFTs Blender add on I'm currently developing please check out our Discord and Github page: