Knot a Problem is an app for quickly designing and creating a Celtic knot.
Design your knot by drawing in the "walls" where the crossings shouldn't be.
Make your knot bigger or smaller, and customise the colour scheme. Export as a picture, or export the code to create your knot in a TeX document.
Learn about Celtic knots by experimenting with different designs.
Up to six family members will be able to use this app with Family Sharing enabled.