I couldn't give up on trying a hexagon mat, so I thought about sewing it to some fabric, right sides together, adding some wadding and turning to the right side.
That was rather fiddly, and may not have been helped by listening to Bat Out Of Hell by Meatloaf! However, eventually, I got it turned all the way through and then machine stitched around the edge to close the pocket, and make it all sit neatly.
I did it, but I think I prefer it appliqued onto fabric, but you never know until you try these things. The crumb block was much more satisfactory.