A simple Companion Cube filet chart!

There are two graphs, with a very slight variation. The circle and heart in the center are slightly different sizes.

Filet is generally done with thread. You can also use baby or sock yarn to filet patterns and keep the pattern visible.

Some worsted weight yarns will show the patterns as well, but bulkier yarns will most likely just crowd the spaces and make it a bit too hard to see.