Waste canvas was used to get the design on a tee shirt. It's sold near the aida cloth in craft stores. If the design was going to take longer I would have basted the canvas to the shirt, but with just two colors, this was relatively fast, so I just pinned it. Once it's in place, you simply do the cross stitching as usual, making sure to place your needle in the tiny squares and not catch the waste canvas threads.
After stitching is complete, cut away the excess canvas. Then wet the waste canvas with a damp rag. This will loosen the glue that holds it together. Next, pull the threads out one by one. (This goes faster than it sounds.) If one seems to resist pulling, wet it more. If that doesn't work, carefully snip at it, it may have gotten caught in the stitching. You can see the tiny squares that you stitch into better in this photo. About half of the threads had been pulled at this stage.