IKEA has a variety of open cabinets for wall storage like EKET cabinets. You can group the square cabinets how you want and choose from colors like light blue, dark blue and light orange. They come in singles, doubles and with four compartments.
Muuto Mini Stacked Shelving - Scandinavian Design at its best - Muuto Mini Stacked system provides a storage solution with infinite potential. Mini Stacked Cubes hang neatly on the wall either individually or together, creating a stylish look