The punch card design I used in my latest machine knit t-shirt is available in my shop. It's free, and it comes with PDF printouts that you can use as templates with blank punch cards and a puncher. If you have a computer-controlled cutting machine, I've also included the SVG file for you to import into your cutting software. If you use the basic version of Silhouette Design Studio, I've also included the Silhouette file for your convenience.
I'm glad I'm able to directly link the ZIP file here, because I'm unable to when I create a shop item. I'll have to rethink how I offer free items in the future. At the moment, the only way to avoid going through the checkout process to download a free digital product is to use the link provided to Google Drive. The image below shows what I mean. Once clicked, Google Drive will show you all the files included in the ZIP file and you can download it on the top right corner of the page. Both ways work, except I must remember to upload the files, and keep them up to date at more than just one place!