String-Art Generator Web App

I need a web app that converts a user's photo into a string-art (thread-art) pattern - the kind of art made by winding a single thread between nails set in a circle. A user uploads a photo (mainly portraits), the app simulates how it would look rendered in thread, and it outputs step-by-step instructions to recreate the piece by hand on a physical board. Reference examples: LetsString and RingString. The output should work the same way. To be clear, this is a deterministic line-optimization (greedy) algorithm, not AI image generation - please don't propose Stable Diffusion, GANs, or diffusion models. The board The board is a circle of nails, and I need support for two sizes: 240 nails and 200 nails. Nails are grouped into four clockwise sectors, A, B, C, D, each a quarter of the circle and numbered 1 to 60: A1 to A60: 9 to 12 o'clock B1 to B60: 12 to 3 o'clock C1 to C60: 3 to 6 o'clock D1 to D60: 6 to 9 o'clock Final instructions must use this labeling (for example: A5, C40, B12, and so on) so the user can follow along on the real board. Thread count (lines) per board size 240 nails: roughly 3,000 to 4,000 lines (finer detail, better for portraits) 200 nails: roughly 2,500 to 3,500 lines Line count should be adjustable in the app so we can tune quality against thread usage per board. What the app should do Let the user upload a photo. Generate 3 variants from that photo (for example, different contrast or line density), shown side by side. Let the user pick their favorite. From the chosen variant, generate the full nail sequence as clear, printable instructions in the A to D plus 1 to 60 format above, along with a preview of the simulated result.