I made thinner version of my previous design, 15x5x0.9 cm, and I made new smaller case 6x6x0.9 cm. On smaller design I used smaller NFC sticker 19x19mm from the same site you posted in competition brief. Both cases are made for BLE chip 5mm thick and could be 1 mm thinner if we made chip 4 mm. I hope you'll be satisfied with this models. I'm sending you and .3ds and .OBJ files with both models inside.
This is model with full color. I'm sending you .max, .3ds and .obj files, .jpeg-s imported in max for front side of case (12,13,14,15), and I'm sending you two .png files if you need to print on transparent adhesive foil.