The Project Background

String art has been an intersection of geometry and craft for decades. My connection to it is personal; I discovered geometric patterns at my grandmother’s house, made by my father during his youth. Before computers were common, he manually connected nails on wooden boards with colored threads. Then I found the art of Petros Vrellis, and it had a big impact on me. I decided to make some portraits with this knitting technique. It turned out great; I made some portraits that are really good to look at, not just because they show my loved ones, but also because my own work is in these pictures. Recently, I found some sites where others are selling overpriced kits for knitting. You have to buy the kit from them just to have the pattern. I think it's outrageous and it should be free. So I decided to make this page; you can start the knitter generator with the button at the top, but I suggest you read all the information on this page. Check out the math behind the generating because it can help you understand which pictures will look good. Also, check out the guiding tool so you can work easier. At the top, there's another button for my other projects. I'm constantly updating those; they are centered around chemistry, physics, and electronics.

Petros Vrellis and Photorealism

About 10 years ago, Petros Vrellis shifted the focus from simple geometry to computer-generated, photorealistic portraits. This process uses a specialized algorithm to determine the path of a single continuous thread.

Open Source Foundation

This generator is based on Christian Siegel’s experiment (published under the MIT License), which recreated Vrellis's approach. My goal was to create a free, transparent tool because many commercial kits lock this logic behind paywalls without providing the necessary practical advice for assembly.

Building the Physical Frame

A durable circular frame is essential. Each of the 3,000 strings adds tension; if the frame deforms, the image quality degrades. I recommend a 90cm wooden gymnastic hoop for its durability and professional look.

My first portraits were on bicycle rims. While functional, drilling them and using superglue was difficult. Wood is much easier to work with and provides a better aesthetic for home decor.

Marking the pins

Once you have the hoop, you need to decide on the number of pins. I suggest at least 200. My generator script is designed to handle slightly more or fewer if needed. The pins must be placed evenly around the circumference.

For a 90cm (35.4") diameter, the circumference is roughly 282.7cm (111.3"). To get about 200 pins, you'd need a 14.135mm (0.55") spacing. Personally, I just rounded this down to exactly 10mm (approx. 0.4") spacing, which gave me 282 pins in total.

Marking takes less than an hour if you make a simple template. Create a small guide that slides along the hoop's surface with two holes drilled exactly 10mm apart. Mark the first pin, slide the template until you see that mark through the second hole, and mark the new pin through the first hole.

Correction at the end: Because of small inaccuracies, the last pin might not be exactly 10mm from Pin 0. If you have a 5mm error, just distribute that gap over the last 10–20 pins by adding 0.5mm to each space. This won't be noticeable to the eye.

Drilling and Assembly

You MUST drill holes. If you try to hammer nails directly into a thin wooden hoop, it will split. Drilling took me about 2 hours using a Dremel. I used a bit that allowed the pins to "wiggle" just a tiny bit.

Pro Tip: It's actually better if the pins lean slightly outward. As the thread becomes taut, it pulls itself toward the base of the pin (the center of the circle). If the pins lean inward, the thread might slip off the top once you have many layers.

I used simple wood glue for the pins. To prevent glue from leaking out the back of the through-holes, I wrapped the back of the hoop in masking tape first. This takes about an hour.

Numbering

You cannot count from zero for every single step. You have to number the pins I used masking tape around the rim to write the numbers. Start with Pin 0 at the top and go clockwise. If you reverse the direction, you mirror the image. You don't need to label every pin—every 5th or 10th is enough. Using different colors for 5s and 10s helps speed things up. 

The Weaving Process

This takes about 16–24 hours of pure work. Make sure your environment is ergonomic:

• Good lighting is essential.
• Print the String Art Instructions PDF and use a marker to cross out steps, or use Excel on a laptop, where you can jump to the cell with a button.
• Set the hoop so the top is a bit higher than eye level—high enough to see the numbers but low enough that your arms don't get too tired.
• Fix the hoop so it doesn't wobble. I tried using rollers to rotate it, but the thread just got tangled in other pins.

Tie the thread to Pin 0. You don't need to knot every pin; just loop around and move on. However, every 5–10 steps, do 3–4 extra turns around a pin. This acts as a "save point" in case the thread breaks or you have to backtrack.

On my 90cm hoop, I planned for 3,000 strings. Around step 2,700, I ran out of my two 1,000-meter spools. The portrait already looked great and recognizable, so I decided to stop there.

Finishing Touches

1. Secure the end: Don't just loop it; tie it off firmly.
2. Glue the pins: To make it "child-proof" and durable, put a drop of thin, clear glue on each pin. Be careful with some superglues, as they can leave a "white fog" (bloom) on the thread.
3. The Background: The art looks best when the strings cast a shadow on a surface very close behind them. I recommend gluing a white sheet of paper to the back of the hoop. I used two flipchart papers glued together.

Finally, add a hanger to the back, and you've successfully completed your string art portrait.