Awhile back I saw this pin and kept thinking I need to do that. It took me longer than I wanted but I finally got around to getting it together. I bought a $1 pack of kids' size clothes hangers. The wire ones may be easier to get the shirts on and off of though. I made these little shirts and punched a hole in the top.
The original pin focused on making sums to 10. Below you can see where we've practiced doing that but I also wanted to include the shirts with numbers 1-10 for preK and kinder friends that are still working on counting and matching the quantity to the number shown.
I chose to use 2 colors of clothespins so that students can get use to seeing numbers in relation to 5. You can download a copy of the shirts here. You'll have to load different colored paper in your printer if you want them to print in multi-colors. Hope your sweeties have fun with them!