It is temporarily glued to cardboard but its permanent home will be glaze-glued to a tile make from L4410P, a zero-fired-shrinkage body suitable for making wall tile.
I 3D-printed a stamper to create 9mm square pixels. Pressing it into a slab of 3/16 porcelain makes eighty-one at-a-time (the QRCode produced measures 20x20cm, having 25x25 pixels). The black porcelain has 5% Mason 6666 stain. Firing temperature was cone 6. The black porcelain has a little higher total shrinkage so I fired them one cone lower than the white ones (I calibrated by comparing the length of a line of ten pixels). The pixels dry and shrink and drop out of the stamper easily. The action of the stamper rounds the upper corners of each. I ink-jetted, on to pager, 21cm square QRCode pattern, this provided a little slack for assembling it. Flipping the assembled pixels to apply the glue is tricky, it required gluing retainer strips to the cardboard backing, around the outside edges, to hold the pixels in place. For the next one I plan to glue the pixels to a zero-fired-shrinkage clay tile, made from L4410P. A little silicon sealant on the tile and that will be suitable outdoors. What does this QRCode say? https://plainsmanclays.com.